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Read the following passage and answer the questions
   Ballpoint pen is a pen that has, as its name says, ball at its point which rotates
when dragged across the writing surface and leaves behind ink that comes from
the reservoir of the pen. Ball at the point can be of different diameter and can be
made of brass, steel, or tungsten carbide. It is today the most widespread writing
instrument and has literally changed the way we write.
   Trying to invent a pen which can write on leather, a tanner John J. Loud
invented the first ballpoint pen and patented it in 1888 in America. This pen had a
small steel ball which was placed so it could not fall out nor fall in but it still
could rotate freely. This invention was not commercially viable and could not be
used for writing. Because of that patent lapsed in time.
1. Where does the ink come from?

________________________________________________
2. What can ball at the point be made of?
________________________________________________
3. Who invented the first ballpoint pen?
________________________________________________
4. Was this invention commercially viable?
________________________________________________

D. WRITING
Complete the second sentence so that it has the same meaning to the first
1. Do you mind if I go out with my friends at night?
Would you mind if __________________________.
2. “Is Ha Long Bay a wonder of the world?” Ann said to me.
Ann asked_________________________________.
3. They decorated their house for the Tet holiday last weekend.
Their house________________________________.
4. Let’s go shopping.
Why don’t we ______________________________?

2
6 tháng 8 2021

1. Where does the ink come from?

__________________ It comes from the reservoir of the pen.______________________________

2. What can ball at the point be made of?
_______________  Ball at the point can be of different diameter and can be made of brass, steel, or tungsten carbide._________________________________

3. Who invented the first ballpoint pen?
________________ John J. Loud________________________________

4. Was this invention commercially viable?
____________ No, it wasn’t.____________________________________

 

D. WRITING
Complete the second sentence so that it has the same meaning to the first
1. Do you mind if I go out with my friends at night?
Would you mind if ____________I went out with my friends at night?______________.
2. “Is Ha Long Bay a wonder of the world?” Ann said to me.
Ann asked_________________ me if Ha Long Bay was a wonder of the world________________.

3. They decorated their house for the Tet holiday last weekend.
Their house___________ was decorated for the Tet holiday last weekend_____________________.

4. Let’s go shopping.
Why don’t we _________go shopping_____________________?

 

6 tháng 8 2021

Read the following passage and answer the questions
   Ballpoint pen is a pen that has, as its name says, ball at its point which rotates
when dragged across the writing surface and leaves behind ink that comes from
the reservoir of the pen. Ball at the point can be of different diameter and can be
made of brass, steel, or tungsten carbide. It is today the most widespread writing
instrument and has literally changed the way we write.
   Trying to invent a pen which can write on leather, a tanner John J. Loud
invented the first ballpoint pen and patented it in 1888 in America. This pen had a
small steel ball which was placed so it could not fall out nor fall in but it still
could rotate freely. This invention was not commercially viable and could not be
used for writing. Because of that patent lapsed in time.
1. Where does the ink come from?

_______It comes from the reservoir of the pen._________________________________________
2. What can ball at the point be made of?
______ Ball at the point can be of different diameter and can be
made of brass, steel, or tungsten carbide.__________________________________________
3. Who invented the first ballpoint pen?
_______John J. Loud
invented the first ballpoint pen _________________________________________
4. Was this invention commercially viable?
_______This invention was not commercially viable_________________________________________

D. WRITING
Complete the second sentence so that it has the same meaning to the first
1. Do you mind if I go out with my friends at night?
Would you mind if ___I went out with my friends at night?_______________________.
2. “Is Ha Long Bay a wonder of the world?” Ann said to me.
Ann asked____me if Ha Long Bay was a wonder of the world _____________________________.
3. They decorated their house for the Tet holiday last weekend.
Their house___was decorated for the Tet holiday last weekend._____________________________.
4. Let’s go shopping.
Why don’t we ____go shopping__________________________?

15 tháng 2 2017

Đáp án là: It can be made of brass, steel, or tungsten carbide.

16 tháng 1 2019

Đáp án là: It comes from the reservoir of the pen.

27 tháng 3 2018

Đáp án là: No, it wasn’t.

15 tháng 4 2019

Đáp án là: John J. Loud invented the first ballpoint pen.

IV. In the following text, six sentences or parts of sentences have been removed. Above the extract you will find the six removed sentences PLUS one sentence which doesn't fit. Choose from the sentences (A-G) the one which fits each gap (1-6). Remember, there is one extra sentence you do not need to use. Write the correct letter in the box. Choose from the following sentences to fill the spaces in the text. There is ONE extra. A. Using a microwave for cooking a large food mass is difficult...
Đọc tiếp

IV. In the following text, six sentences or parts of sentences have been removed. Above
the extract you will find the six removed sentences PLUS one sentence which doesn't fit.
Choose from the sentences (A-G) the one which fits each gap (1-6). Remember, there is
one extra sentence you do not need to use. Write the correct letter in the box.
Choose from the following sentences to fill the spaces in the text. There is ONE extra.
A. Using a microwave for cooking a large food mass is difficult due to limited penetration of
microwaves.
B. This can be overcome by leaving the food to stand for a few minutes when cooking is
completed.

C. It is advised that the water should be poured slowly into another container that already
contains the powder.
D. In this way, buying a microwave oven with a turntable ensure the food is cooked
throughout.
E. Conversely the microwaves do not heat glass, ceramic and plastic containers.
F. If the microwaves are not absorbed inside the oven, the oven can be damaged by
electrical arcs and overheating of the microwave source.
G. When water in that state is disturbed, it can suddenly and unexpectedly boil violently.
MICROWAVING
Microwaving is a method of cooking where food is bombarded by microwaves, usually
within an appliance called a microwave oven which excite the water, fat and sugar
molecules, thereby heating (cooking) both the outside and center of the food at the same
time. (1)…………………
(A common myth is that a microwave oven cooks from the center of the food outward. This
appears to happen because heat generated at the surface escapes more readily from the
surface of the food into the surrounding air.) One advantage of microwaving is that small
amounts of food can be heated very quickly, making it useful for reheating leftovers.
The disadvantage is that food which is microwaved does not undergo some of the chemical
reactions, such as browning, which makes the food visually attractive. Primitive microwave
ovens often do not cook evenly, leading to a concern that bacteria easily killed by more
traditional cooking methods may survive the quick cooking time in "cold spots", though the
food item as a whole is cooked to a safe average temperature. (2) ……
Some high-end microwave ovens are combined with a convection oven which basically
cook the food using microwave and hot air simultaneously to achieve both the fast cooking
time and browning effect.
(3) …………………
However microwave ovens are used in some fast food chains and special microwave bags
are available for cooking fowl or large joints of meat.
Professional chefs generally recommend using microwaves for a limited set of tasks,
including: melting fats (such as butter) and chocolate, cooking grains like oatmeal and grits,
cooking rice, thawing frozen meats and vegetables before cooking by other methods and
quickly reheating already-cooked foods.
Using a microwave to boil water is potentially dangerous, due to superheating. In a
microwave, water can be raised quickly to a temperature above the boiling point before
major bubbles form, especially if it is purified and in a very clean glass vessel. (4)
…………………
This effect is rare, even for scientists who try to deliberately recreate it, and any seed
whatsoever for boiling is likely to prevent the problem. Boiling water with, for instance, a
teabag already in it will prevent any dangers by providing a seed, as will using a mug that is
not perfectly clean.

The risk greatly increases when water has already been boiled once in the same container.
This situation can occur if the user of the oven boiled the water once, forgot about it, then
came back later to boil it again. The first time the water boils, the seed bubbles
(microscopic bubbles of air around which larger steam bubbles grow) are used up and
largely eliminated from the water as it cools down. When the water is heated again, the lack
of seed bubbles causes superheating, and a risk of a steam explosion when the water's
surface is disturbed.
Placing something in the water before heating can mostly alleviate this risk. If you are
planning to mix something with the water, say tea or hot chocolate, adding it before heating
will insure that the water boils. Otherwise, placing a wood object, for instance a chopstick,
in the water before heating will also work.
Care should be taken when removing heated water from a microwave. Make sure that the
hands are protected from possible liquid boil-over, place the container on a level, heat-
proof surface and stir liquid with a warm spoon. Also, never add powdered substances
(such as instant coffee or cocoa mix) to the container taken from the microwave, due to the
addition of all those seed bubbles and the potential for violent, spontaneous boiling. (5)
…………………
Metal objects, such as metal utensils, in a microwave oven can lead to dangerous situations.
Metals do not absorb microwaves effectively. Instead, metals reflect microwaves, thereby
preventing the latter from reaching the food. (6) …………………
Thin metal layers, such as metal foil and mugs with metal trim can melt or burn due to the
strong electrical currents that are generated in metal objects. However, small solid metal
objects, such as spoons, in combination with a large amount of absorbing food or liquid,
normally do not lead to problems.
This article is licensed under the GNU Free Documentation License. It uses material from the
Original Wikipedia article.

3
21 tháng 2 2020

IV. In the following text, six sentences or parts of sentences have been removed. Above
the extract you will find the six removed sentences PLUS one sentence which doesn't fit.
Choose from the sentences (A-G) the one which fits each gap (1-6). Remember, there is
one extra sentence you do not need to use. Write the correct letter in the box.
Choose from the following sentences to fill the spaces in the text. There is ONE extra.
A. Using a microwave for cooking a large food mass is difficult due to limited penetration of
microwaves.
B. This can be overcome by leaving the food to stand for a few minutes when cooking is
completed.

C. It is advised that the water should be poured slowly into another container that already
contains the powder.
D. In this way, buying a microwave oven with a turntable ensure the food is cooked
throughout.
E. Conversely the microwaves do not heat glass, ceramic and plastic containers.
F. If the microwaves are not absorbed inside the oven, the oven can be damaged by
electrical arcs and overheating of the microwave source.
G. When water in that state is disturbed, it can suddenly and unexpectedly boil violently.
MICROWAVING
Microwaving is a method of cooking where food is bombarded by microwaves, usually
within an appliance called a microwave oven which excite the water, fat and sugar
molecules, thereby heating (cooking) both the outside and center of the food at the same
time. (1)………E…………
(A common myth is that a microwave oven cooks from the center of the food outward. This
appears to happen because heat generated at the surface escapes more readily from the
surface of the food into the surrounding air.) One advantage of microwaving is that small
amounts of food can be heated very quickly, making it useful for reheating leftovers.
The disadvantage is that food which is microwaved does not undergo some of the chemical
reactions, such as browning, which makes the food visually attractive. Primitive microwave
ovens often do not cook evenly, leading to a concern that bacteria easily killed by more
traditional cooking methods may survive the quick cooking time in "cold spots", though the
food item as a whole is cooked to a safe average temperature. (2) …B
Some high-end microwave ovens are combined with a convection oven which basically
cook the food using microwave and hot air simultaneously to achieve both the fast cooking
time and browning effect.
(3) ………A…………
However microwave ovens are used in some fast food chains and special microwave bags
are available for cooking fowl or large joints of meat.
Professional chefs generally recommend using microwaves for a limited set of tasks,
including: melting fats (such as butter) and chocolate, cooking grains like oatmeal and grits,
cooking rice, thawing frozen meats and vegetables before cooking by other methods and
quickly reheating already-cooked foods.
Using a microwave to boil water is potentially dangerous, due to superheating. In a
microwave, water can be raised quickly to a temperature above the boiling point before
major bubbles form, especially if it is purified and in a very clean glass vessel. (4)
………G…………
This effect is rare, even for scientists who try to deliberately recreate it, and any seed
whatsoever for boiling is likely to prevent the problem. Boiling water with, for instance, a
teabag already in it will prevent any dangers by providing a seed, as will using a mug that is
not perfectly clean.

The risk greatly increases when water has already been boiled once in the same container.
This situation can occur if the user of the oven boiled the water once, forgot about it, then
came back later to boil it again. The first time the water boils, the seed bubbles
(microscopic bubbles of air around which larger steam bubbles grow) are used up and
largely eliminated from the water as it cools down. When the water is heated again, the lack
of seed bubbles causes superheating, and a risk of a steam explosion when the water's
surface is disturbed.
Placing something in the water before heating can mostly alleviate this risk. If you are
planning to mix something with the water, say tea or hot chocolate, adding it before heating
will insure that the water boils. Otherwise, placing a wood object, for instance a chopstick,
in the water before heating will also work.
Care should be taken when removing heated water from a microwave. Make sure that the
hands are protected from possible liquid boil-over, place the container on a level, heat-
proof surface and stir liquid with a warm spoon. Also, never add powdered substances
(such as instant coffee or cocoa mix) to the container taken from the microwave, due to the
addition of all those seed bubbles and the potential for violent, spontaneous boiling. (5)
…………C………
Metal objects, such as metal utensils, in a microwave oven can lead to dangerous situations.
Metals do not absorb microwaves effectively. Instead, metals reflect microwaves, thereby
preventing the latter from reaching the food. (6) …………F………
Thin metal layers, such as metal foil and mugs with metal trim can melt or burn due to the
strong electrical currents that are generated in metal objects. However, small solid metal
objects, such as spoons, in combination with a large amount of absorbing food or liquid,
normally do not lead to problems.
This article is licensed under the GNU Free Documentation License. It uses material from the
Original Wikipedia article.

21 tháng 2 2020

Nguyễn Bích Ngọc ngô mai phương một tip nhỏ cho 2 e khi làm bài này đúng ra là nên đọc hết cả bài nhưng mà cj thấy bài này sử dụng từ vựng khá là đơn giản thôi nên chỉ cần đọc câu trước và câu phía sau câu chỗ cần điền các e có thể đoán ra phần nào cho chắc ăn các e có thể đọc lại đoạn đó sau khi chọn. < chỉ bài này thôi là đọc câu trước và câu sau là tìm dduocj thôi chứ cj ko chắc là bài nào cũng vậy nah >

IV.Choose the best answer.(2pts) 1.People from other planets may use ___________ to communicate, which is not possible for human beings. A.landlines B.letters C.chat rooms D.telepathy 2.I prefer __________ a nine-to-five job to working shifts. A.did B.doing C.do 3. Facebook was built on the ………of earlier social network sites like MySpace and Bebo. A. succeed B. successful C. successfully D. success 4.She said she __________ to the Moon when she had enough money. ...
Đọc tiếp

IV.Choose the best answer.(2pts)
1.People from other planets may use ___________ to communicate, which is not possible for human beings.
A.landlines B.letters C.chat rooms D.telepathy
2.I prefer __________ a nine-to-five job to working shifts.
A.did B.doing C.do
3. Facebook was built on the ………of earlier social network sites like MySpace and Bebo.
A. succeed B. successful C. successfully D. success
4.She said she __________ to the Moon when she had enough money.
A.travelled B.to travel C.would travel
5.I intended __________ to New York next month.
A.flew B.to fly C.fly

6.Alexander Graham Bell was a great ___________, who invented the telephone.
A.developer B.conservationist C.scientist D.explorer
7.If you __________ something, you should patent it as quickly as possible.
A.invented B.will invent C.have invented D.are inventing
8.___________ systems use several different ways of giving information with sounds, pictures, and texts on a screen.
A.Emailing B.Telephoning C.Multimedia D.Chatting
IV. Read the text and choose T/F.(2pts)
Texting is a new way of exchanging information, and it is becoming more and more popular among the young. In fact, texting is clearly affecting language. There are no rules for it. We are creating a new aspect of vocabulary and opening up a new kind of playful and direct communication. Naturally, texting is fun and that’s fine, but some people are wo
ied about the effects it might have on a child’s ability to read and write. But not everyone is so wo
ied. An expert says, “Every time a new medium comes along it has an effect on language … But this doesn’t destroy the existing language, it adds to it.” In text messages, many words come from shorthand created in email, such as CUS (See you soon) and so on. Someone says, “Mostly they are original, but sometimes you get a clash of meanings. For example, LOL can mean both Laugh Out Loud and Lots of Love. That could lead to some misunderstandings.”
1.There are no rules for texting.
2.Texting is always affecting language in a bad way.
3.Everyone is wo
ied about texting.
4.A child should not write text messages.

1
18 tháng 5 2019

IV.Choose the best answer.(2pts)
1.People from other planets may use ___________ to communicate, which is not possible for human beings.
A.landlines B.letters C.chat rooms D.telepathy
2.I prefer __________ a nine-to-five job to working shifts.
A.did B.doing C.do
3. Facebook was built on the ………of earlier social network sites like MySpace and Bebo.
A. succeed B. successful C. successfully D. success
4.She said she __________ to the Moon when she had enough money.
A.travelled B.to travel C.would travel
5.I intended __________ to New York next month.
A.flew B.to fly C.fly
6.Alexander Graham Bell was a great ___________, who invented the telephone.
A.developer B.conservationist C.scientist D.explorer
7.If you __________ something, you should patent it as quickly as possible.
A.invented B.will invent C.have invented D.are inventing
8.___________ systems use several different ways of giving information with sounds, pictures, and texts on a screen.
A.Emailing B.Telephoning C.Multimedia D.Chatting
IV. Read the text and choose T/F.(2pts)
Texting is a new way of exchanging information, and it is becoming more and more popular among the young. In fact, texting is clearly affecting language. There are no rules for it. We are creating a new aspect of vocabulary and opening up a new kind of playful and direct communication. Naturally, texting is fun and that’s fine, but some people are wo
ied about the effects it might have on a child’s ability to read and write. But not everyone is so wo
ied. An expert says, “Every time a new medium comes along it has an effect on language … But this doesn’t destroy the existing language, it adds to it.” In text messages, many words come from shorthand created in email, such as CUS (See you soon) and so on. Someone says, “Mostly they are original, but sometimes you get a clash of meanings. For example, LOL can mean both Laugh Out Loud and Lots of Love. That could lead to some misunderstandings.”
1.There are no rules for texting. T
2.Texting is always affecting language in a bad way. T
3.Everyone is wo
ied about texting. F
4.A child should not write text messages.T

Rewrite the sentences given about the Thai traditions and customs, using the following expressions. You can add some words or make changes where's a tradition that according to the tradition follow the tradition of break with tradition by have the custom of 1. Visitors should dress nearly in all religious shrines and temples, and never enter in sheeveless...
Đọc tiếp

Rewrite the sentences given about the Thai traditions and customs, using the following expressions. You can add some words or make changes
where's a tradition that
according to the tradition
follow the tradition of
break with tradition by
have the custom of

1. Visitors should dress nearly in all religious shrines and temples, and never enter in sheeveless shirts.
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
2. Never climb onto a Buddha image to take a photograph or do anything that might indicate a lack of respect.
________________________________________________________________________________________________________________________________________________________________________________________________________
3. A monk is not allowed to touch money, so if a man wishes to give money to a monk , be must place it in the bowl.
____________________________________________________________________________________________________
4. The "wai" - a slight bow with the palms together and the fingertips touching the face - is a way of showing respect or thanks, but you can smile of nod.
________________________________________________________________________________________________________________________________________________________________________________________________________
5. Shoes should be removes when entering a private Thai home as a sign of respect.
________________________________________________________________________________________________________________________________________________________________________________________________________
6. You should never point your feet at someone or an object as this is considered disrespectful.
________________________________________________________________________________________________________________________________________________________________________________________________________
7. It is considered very rude to touch people on the head, but now you can touch young children on their head.
________________________________________________________________________________________________________________________________________________________________________________________________________
8. You can use the word "Khun" as the best way to address someone and it is used in front of the name, usually the first name.
________________________________________________________________________________________________________________________________________________________________________________________________________

0
I. Write sentences with the cue words, using the past progressive tense. They/ play/ tennis/ 10.30 yesterday morning. Ann/ do/ homework/ 5 o’clock this afternoon. My father/ wash/ car/ from/ five to six. This time last year/ we/ live/ France. The students/ offer/ flowers/ the visitors. I/ cook/ dinner/ half an hour ago. She/ work/ the studio/ that time. What/ you/ do/ from 3 to 6 yesterday afternoon? I/ write/ my report/ 8 o’clock last night. II. Put the verbs into correct form: past...
Đọc tiếp

I. Write sentences with the cue words, using the past progressive tense.
They/ play/ tennis/ 10.30 yesterday morning.
Ann/ do/ homework/ 5 o’clock this afternoon.
My father/ wash/ car/ from/ five to six.
This time last year/ we/ live/ France.
The students/ offer/ flowers/ the visitors.
I/ cook/ dinner/ half an hour ago.
She/ work/ the studio/ that time.
What/ you/ do/ from 3 to 6 yesterday afternoon?
I/ write/ my report/ 8 o’clock last night.
II. Put the verbs into correct form: past progressive or past simple.
The doorbell (ring) ______ while Tom (watch) _______ television.
How fast _______ you _______ (drive) when the accident (happen) ______ ?
Anna and Susan (make) ______ dinner when Martin (arrive) ______ home.
The light (go) ______ out while we (have) ______ dinner. But it (come) ______ again after about ten minutes.
“What _______ you (do) ______ this time yesterday?” – I (work) ______ on the computer.”
It suddenly (begin) ______ rain while Laura (sit) ______ in the garden.
It (be) ______ cold when we (leave) ______ the house that day, and a light snow (fall) _______.
When I last (see) ______ them, they (try) ______ to find a new house near their work.
I (walk) _______ along the street when I suddenly (feel) ______ something hit me in the back. I (not/ know) _______ what it was.
When we (drive) _______ down the hill, a strange object (appear) _______ in the sky.
III. Complete the passage with the most suitable words.
Torquay is one of the (1) ______ popular holiday resorts in Britain. (2) ______ provides entertainment, sports of every kind, etc. You can (3) ______ at the hotels by the sea, or at a comfortable expensive (4) ______ houses. There (5) ______ camping sites, too. Torquay has large sandy beaches (6) ______ you can buy refreshments and hire (7) ______ to sit on. There are large areas of grass land and miles of cliff paths (8) ______ walkers.
IV. Read the passage, then answer the questions.
New York City is located in the southeastern part of New York State just east of New Jersey. The city was found by the Dutch in 1624. At first is called Fort Amsterdam, and then New Amsterdam. In 1664, the English took over the city and renamed it New York. With the population of more than 7 millions in the city and 19 million in the metropolitan region, New York is the largest city in the United States. It is divided into five parts, which are Manhattan, the Bronx, Brooklyn, Queens, and Staten Island. The total area of these parts is 946 square kilometers. Visitors to New York are all attracted by places such as the Statue of Liberty, the Empire State Building, Wall Street, and Broadway theater district. New York is also where tourists can visit some world famous art galleries and museums.
Where is New York City?
Why was New York originally called New Amsterdam?
When was it found?
What is its population?
How many parts are there in the city?
How big is it?
What are visitors to New York attracted by?

8
10 tháng 1 2018

III

Torquay is one of the (1) ____most_____ popular holiday resorts in Britain. (2) ___It_____ provides entertainment, sports of very kind, etc. You can (3) ____live____ at the hotels by the sea, or at comfortable but less expensive (4) ___than_____ houses. There (5) ___are_____ camping sites too. Torquay has large sandy beaches (6) ___where_____ you can buy refreshment and hire (7) ____chairs (ko chắc lắm)____ to sit on. There are areas of grass land and miles of cliff paths (8) ____for____ walkers.

10 tháng 1 2018

-Where is New York City ?

=> In the south of teh USA

- Why was New York originally called New Amsterdam?

=> Because it was founded by the Dutch .

- When was it found?

=>The city was found by the Dutch in 1624

-What is its population?

=> 26million

-How many parts are there in the city?

=> The city was named New York by the Dutch .

- What are visitors to New York attracted by?

=> Visitors to New York are all attracted by places such as the Statue of Liberty, the Empire State Building, Wall Street, and Broadway theater district.

NẾU NHƯ SAI THJ THUI NHA !!tẠI VÌ MK TỰ LÀM KO CHẮC ĐÂU ĐÓ NHEN!!!

MICROWAVING Microwaving is a method of cooking where food is bombarded by microwaves, usually within an appliance called a microwave oven which excite the water, fat and sugar molecules, thereby heating (cooking) both the outside and center of the food at the same time. (1)………………… (A common myth is that a microwave oven cooks from the center of the food outward. This appears to happen because heat generated at the surface escapes more readily from the surface of the food into the...
Đọc tiếp

MICROWAVING
Microwaving is a method of cooking where food is bombarded by microwaves, usually
within an appliance called a microwave oven which excite the water, fat and sugar
molecules, thereby heating (cooking) both the outside and center of the food at the same
time. (1)…………………
(A common myth is that a microwave oven cooks from the center of the food outward. This
appears to happen because heat generated at the surface escapes more readily from the
surface of the food into the surrounding air.) One advantage of microwaving is that small
amounts of food can be heated very quickly, making it useful for reheating leftovers.
The disadvantage is that food which is microwaved does not undergo some of the chemical
reactions, such as browning, which makes the food visually attractive. Primitive microwave
ovens often do not cook evenly, leading to a concern that bacteria easily killed by more
traditional cooking methods may survive the quick cooking time in &quot;cold spots&quot;, though the
food item as a whole is cooked to a safe average temperature. (2) ……
Some high-end microwave ovens are combined with a convection oven which basically
cook the food using microwave and hot air simultaneously to achieve both the fast cooking
time and browning effect.
(3) …………………
However microwave ovens are used in some fast food chains and special microwave bags
are available for cooking fowl or large joints of meat.
Professional chefs generally recommend using microwaves for a limited set of tasks,
including: melting fats (such as butter) and chocolate, cooking grains like oatmeal and grits,
cooking rice, thawing frozen meats and vegetables before cooking by other methods and
quickly reheating already-cooked foods.
Using a microwave to boil water is potentially dangerous, due to superheating. In a
microwave, water can be raised quickly to a temperature above the boiling point before
major bubbles form, especially if it is purified and in a very clean glass vessel. (4)
…………………
This effect is rare, even for scientists who try to deliberately recreate it, and any seed
whatsoever for boiling is likely to prevent the problem. Boiling water with, for instance, a
teabag already in it will prevent any dangers by providing a seed, as will using a mug that is
not perfectly clean.

The risk greatly increases when water has already been boiled once in the same container.
This situation can occur if the user of the oven boiled the water once, forgot about it, then
came back later to boil it again. The first time the water boils, the seed bubbles
(microscopic bubbles of air around which larger steam bubbles grow) are used up and
largely eliminated from the water as it cools down. When the water is heated again, the lack
of seed bubbles causes superheating, and a risk of a steam explosion when the water&#39;s
surface is disturbed.
Placing something in the water before heating can mostly alleviate this risk. If you are
planning to mix something with the water, say tea or hot chocolate, adding it before heating
will insure that the water boils. Otherwise, placing a wood object, for instance a chopstick,
in the water before heating will also work.
Care should be taken when removing heated water from a microwave. Make sure that the
hands are protected from possible liquid boil-over, place the container on a level, heat-
proof surface and stir liquid with a warm spoon. Also, never add powdered substances
(such as instant coffee or cocoa mix) to the container taken from the microwave, due to the
addition of all those seed bubbles and the potential for violent, spontaneous boiling. (5)
…………………
Metal objects, such as metal utensils, in a microwave oven can lead to dangerous situations.
Metals do not absorb microwaves effectively. Instead, metals reflect microwaves, thereby
preventing the latter from reaching the food. (6) …………………
Thin metal layers, such as metal foil and mugs with metal trim can melt or burn due to the
strong electrical currents that are generated in metal objects. However, small solid metal
objects, such as spoons, in combination with a large amount of absorbing food or liquid,
normally do not lead to problems.
This article is licensed under the GNU Free Documentation License. It uses material from the
Original Wikipedia article.

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