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29 tháng 1 2019

Đáp án là C. “and” nối hai từ có chức năng như nhau, trước là danh từ “the mass of the objects” => sau cũng là cụm danh từ.

Read the passage and choose the best answer.A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine...
Đọc tiếp

Read the passage and choose the best answer.

A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms. 

 According to the passage, the distance between a radar set and an object can be determined by _______.  

A. the time it takes for a burst of radio waves to produce echoes when the waves bounce off the object 

B. the term “ranging” used for detection of the distance between an object and the radar set 

C. the time it takes for the radio waves to produce echoes and bounce off the object 

D. the time it takes for the echoes produced by the radio waves to return to the radar set

1
13 tháng 12 2018

Giải thích: Dựa vào “The echo of the sounds against the walls helps a person determine the size of the cave.”

Đáp án  D

9 tháng 7 2018

Có 61 cây thường xuyên từ đầu đường đến cuối của nó. Khoảng cách giữa hai cây liên tiếp là 3m. Đường dài bao lâu?

 giống như chăn lẻ vậy

chặn là cây 

lẻ là đường

chặn , lẻ cứ như vậy khi mô đủ 61 chặn

có tất cả số lẻ là : 61 x 2 - 61 = 61 lẻ => có 61 đường

đường dài só mét là : 61 x 3 = 183 m 

14 tháng 10 2021

C

7 tháng 3 2017

KQ là:173.tk và kb nha

7 tháng 3 2017

kết quả là 173 bạn nhé

kích cho mình nhé bạn kết bạn với mình đi

Read the passage and choose the best answer.A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine...
Đọc tiếp

Read the passage and choose the best answer.

A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms. 

According to the passage, what can radar detect besides location of objects?  

A. Shape.            

B. Size.                 

C. Speed.              

D. Weight.  

1
20 tháng 3 2019

Giải thích: Dựa vào “Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving.”

Đáp án  C

20 tháng 3 2022

This festival is held in my country every 2 years

What is the distance between NYC and Boston?

20 tháng 3 2022

1 . this festival is held in my country every 2 years

 

2 . what is the distance between NYC and Boston?

27 tháng 7 2018

Dịch ra tiếng việt là: Tổng 2 số lẻ là 112 .Tìm 2 số đó nếu ở giữa chúng có 6 số lẻ

Bài giải:

Hiệu 2 số đó là: 6x2=12

Số bé là: (112-12):2 = 50

Số lớn là: 112 -50 = 62

                                       Đáp số: Số bé: 50

                                                    Số lớn: 62

Chúc bạn học tốt.

28 tháng 7 2018

Bạn Pham Van Hung ơi hai số lẻ cơ mà bạn