Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Read the text then choose the best answer to fill in the blanks.
LEARNING A SECOND LANGUAGE
Some people learn a second language (1)_____. Other people have trouble learning a new language . How can you have (2)_____learn a new language , such as English ? There are several ways to make learning English a little (3)_____and more interesting .
The first step is to feel positive about learning English . If you believe that you can learn,you will learn .(4)____patient.You do not to have to understand(5)____all at once . It `s natural to make mistakes when you learn something new . We can learn from our mistakes .
The second step is to practice your English. For example , write in a journal, or diary ,every day. You will get used to (6)_____in English , and you will feel comfortable expressing your ideas in English . After several weeks, you will see that your writing is improving .(7)_____,you much speak English every day. You can practice with your classmates (8)_____class.
The third step is to keep a record of your language learning . You can write this in your journal . After (9)_____class , think about what you did . Did you answer a question(10)_____? Did you understand something the teacher explained?Perhaps the lesson was difficult , but you tried to understand it .
It is important to practice every day and make a record of your achievements .
1. A. ease B. easy C. easily D. all a, b, c.
2. A. itself B. yourself C. himself D. herself
3. A. ease B. easy C. easily D. easier
4. A. Be B. Being C. To be D. Been
5. A. anything B. nothing C. everything D. something
6. A. write B. writing C. to write D. written
7. A. In addition B. Addition C. Additional D. By addition
8. A. of side B. outside C. beside D. byside
9. A. some B. each C. all D. few
10. A. correct B. correction C. correctly D. corrective
III. Choose the best answer to complete these following sentences
1. The boy asked me what the rubber knife was used for.
He said, “ __________?”.
A. What was this rubber knife used for B. What this rubber knife was used for
C. What is this rubber knife used for D. what this rubber knife is used for
If you want to know about a word, check it up in a _________ .
A. book B. tape C. dictionary D. magazine
2. My memory is poor. I can’t learn these new words _________ .
A. in mind B. in heart C. of mind D. by heart
3. Can you _________ any foreign languages?
A. say B. tell C. speak D. talk
4. Our class always _________ at 7 and _________ at 11 a.m.
A. begin/ finish B. start/ end C. come/ leave D. both a and b
5. After completing the basic class of computing, you can _________a high course.
A. come B. have C. attend D. go
6. Our teacher often give us _________ beside the in-class assignments.
A. housework B. homework C. part-time work D. full time work
7. She told me to pass the written _________ before taking the oral exam.
A. show B. examination C. work D. task
8. In order _______ your writing, you have to read a lot and write English as much as
possible.
A. to improve B. to excel C. to pass D. to increase
9. What _________ of learning English do you find most difficult?
A. form B. type C. kind D. aspect
10. I want to go to the International language school. All the teachers there are_________
A. good-qualified B. well-qualified C. enough qualified D. qualified
11. Look at this _________in today’s edition of the Vietnam News, Nam.
A. advertisement B. advertising C. advertise D. advertment
12. If Mary studies harder, she _________pass the final exam.
A. could B. might C. mustD. will
13. If you give me your willing help, I _________ get success.
A. would B. must C. can D. could
14. If you want to get good marks for the test, you _________try harder.
A. has to B. must C. had to D. will
15. You _________ do morning exercise regularly if you want to be healthy.
A. should B. ought to C. had to D. Both a and b
16. You _________ to pass the pretest if you want to take the written exam.
A. have B. ought C. should D. will
17. “ We always try to please you”. She says to me _________ .
A. we always tried to please me B. they always tried to please me.
C. we always try to please me D. they always try to please me.
18. “ Be careful! The paint is wet”, she shouted.
A. She said be careful because the paint was wet.
B. She told me be careful because the paint was wet.
C. She asked me to be careful because the paint is wet.
D. She told me to be careful because the paint was wet.
19. “Can I make an appointment to see the doctor?”
A. Jenny asked to see the doctor.
B. Jenny asked if the doctor could make an appointment.
C. Jenny asked whether she can make an appointment the doctor.
D. Jenny asked if she could make an appointment to see the doctor.
20. “Did they tell you when they left school?”, he said to me.
In reported speech, this could be read: _________
A. He asked me if they told me when they left school.
B. He asked me if they told me when they had left school.
C. He asked me if they had told me when they left school.
D. He asked me if they had told me when they had left school.
21. She asked me how old Jimmy was.
In direct speech, this could be read: _________
A. She asked, “How old Jimmy was?” B. She asked, “How old Jimmy is?”
C. She asked, “How old was Jimmy?” D. She asked, “How old is Jimmy?”
22. “When did your sister arrive?”, he asked.
A. He asked me when my sister arrived.
B. He wanted to know when my sister arrived.
C. He asked me when my sister had arrived.
D. He wanted to know when had my sister arrived.
23. Is she working here?-No, not any more, but she _________
A. use to be B. used to C. use to work D. used to work
24. My friends come to visit me _________time _________
A. by/ to B. from/ to C. for/ in D. at/ to
25. He _________arrive at the office on time.
A. used always to B. used to C. always used to D. used to always
1.C. What is this rubber knife used for ,C. dictionary
2. D. by heart
3. C. speak
4. D. both a and b
5. C. attend
6. B. homework
7. B. examination
8. A. to improve
9. D. aspect
10.B. well-qualified
11. A. advertisement
12.D. will
13.C. can
14.A. has to
15. D. Both a and b
16.A. have
17. B. they always tried to please me.
18.D. She told me to be careful because the paint was wet.
19.D. Jenny asked if she could make an appointment to see the doctor.
20. D. He asked me if they had told me when they had left school.
21. D. She asked, “How old is Jimmy?”
22. C. He asked me when my sister had arrived.
23. D. used to work
24. C. for/ in
25. B. used to
I. Choose the best answer to complete the sentence.
1. Do you often go out.............Saturday evenings?
a. in b. at c. on d. for
2. It's important .................... children to read as many book as possible
a for b. to c. of d. with
4. Poor Kevin! He doesn't know what...........
a, is doing b. to do c. is doing d. for doing
5. The Internet is a very fast and convenient way for people to ..................information
a. look b. get c.do d. make
6. He wants to join the club when he's..............
a. too old d. old enough c. enough old b. so old
7. The Ihternet is dangerous.................viruses and bad programs.
d. because of a. therefore b. however c. despite
8. Mai asked me................. my English teacher looked like.
a. what b. how c. which c.why
9. If you want to attend the course, you................pass the written exam.
a, should b. must c.can d. might
10. "i've passed the examination." " ........."
a. Congratulations! b. All right! d. Never mind. c. Thanks a lot.
Choose the best answer to complete these following sentences
1. They couldn’t pass the final____________.
A. exam B. examine C. examining D. examination
2. We have many well ______ teachers here.
A. qualify B. quality C. qualified D. qualification
3. This shirt costs______88,000VND.
A. approximative B. approximately C. approximation D. approximate
4. If you study at the Brighton Language Center- UK, you can live in ______on campus.
A. dormitory B. mobile room C. hotel D. private room
5. I saw your school’s ______in today’s edition of the Vietnam News.
A. advertise B. advertisement C. advertiser D. advertising
6. I can complete a ______ English test if you want.
A. speak B. spoke C. spoken D. speaking
7. She said that she______ learning English with you.
A. like B. liked C. liking D. to like
8. The government supplied the victims______ food and water.
A. to B. with C. on D. for
9. She asked me where I ______from.
A. come B. came C. to come D. coming
10. What aspects of ______ English do you find difficult?
A. study B. studied C. learnt D. learning
11. If you want to attend the course, you______pass the examination.
A. have to B. has to C. had to D. could
12. She______me whether I liked classical music or not.
A. ask B. asks C. asked D. asking
13. He asked me who the editor of this book______.
A. is B. are C. was D. were
14. He told me he______ leave the city the following day.
A. will have to B. would have to C. has to D. had to
15. He wants to know whether I ______ back tomorrow.
A. come B. will come C. would come D. came
16. I wonder why he______ love his family.
A. doesn’t B. don’t C. didn’t D. hasn’t
17. Mary, have you seen our school’s ______in today edition’s of the “ Times”?
A. advertising B. advertisement C. advertiser D. advertise
18. How can we remember all these vocabulary items?- Well, ______.
A. read them in mind B. study them in heart
C. learn them by heart D. tell them by heart
19. Can you tell me the ______ date of the final exam?
A. same B. good C. ready D. exact
20. I’ve read your advertisement in today’s __________of the “ Tuoi Tre”
A. edit B. editor C. editing D. edition
21. In order to attend a higher course of writing you have__________ the English pretest.
A. to get B. to pass C. to finish D. to study
22. He was a strict __________, he asked me a lot of difficult questions.
A. examine B. examining C. examination D. examiner
23. Books in our school library are __________for us to use.
A. available B. willing C. suitable D. worth
24. I’d like __________an advanced course of computing. Is there any available?
A. to go B. to work with C. to attend D. to have
25. If you want any further__________ you can contact their head office.
A. questions B. information C. answer D. responses
26. How can I remember these grammar rules?- Well, try to do all the __________ exercises in this grammar book.
A. studying B. working C. learning D. grammar
27. You should try harder to pass the__________ . It’s the most important one of the term.
A. questionnaire B. final exam C. pretest D. funny quiz
28. If you want to improve your English, you __________ practice it every day.
A. can B. had to C. must D. may
29. I feel sick. I think you __________see the doctor if you want to get well.
A. can B. may C. ought to D. had to
30. If you want to get good marks, you __________ study harder.
A. must B. could C. will D. shall
31. Unless you hurry, we __________ catch the bus.
A. can B. can’t C. must D. mustn’t
32. He asked her __________
A. when she leaves the party. B. when did she leave the party.
C. when she left the party D. when does she leave the party.
33. He said, “ I bought this book yesterday.” -> He told me that __________
A. he bought the book yesterday. B. he had bought the book yesterday
C. he had bought the book the day before D. he bought the book the previous day.
34. He said that we would be met at the airport, but in fact, we__________
A. wouldn’t B. couldn’t C. didn’t D. weren’t
35. He wanted to know __________there
A. how long time I had been B. how long I had been
C. how long time had I been D. how long had I been
36. She asked me what time it was.
In direct speech this should be read: __________
A. She asked, “ What time it is? B. She asked, “ What time it was?”
C. She asked, “ What time is it?” D. She asked, “ What time was it?”
37. “ Whose motorbike did you borrow last night?”, he asked.
In reported speech this should be read: __________
A. He asked me whose motorbike did I borrow last night.
B. He asked me whose motorbike had I borrowed last night.
C. He asked me whose motorbike I had borrowed last night.
D. He asked me whose motorbike I had borrowed the night before.
38. “ Would you like a cup of coffee?”, she asked.
A. She asked if I like a cup of coffee. B. She asked if I would like a cup of coffee.
C. She asked if I liked a cup of coffee. D. She invited me to have a cup of coffee.
39. “ Did you close the windows when you left?”, ha asked.
A. He asked me if I closed the windows when I left.
B. He asked me if I had closed the windows when I left.
C. He asked me if I closed the windows when I had left.
D. He asked me if I had closed the windows when I had left.
40. Are you a school bus driver?- No, not any more, but I __________
A. used to B. used to be C. use to D. use to be
41. “ What are you going to do this weekend?”, she asked
A. She wanted to know what I am going to do that weekend.
B. She wanted to know what I was going to do this weekend.
C. She wanted to know what I were going to do that weekend.
D. She wanted to know what I was going to do that weekend.
42. Can I help you?- Yes, do you know__________?
A. when the bus come B. when the bus comes
C. when the bus came D. when will the bus come
43. She told me that her mother __________ to market when I arrived.
A. just went B. had just gone C. has just gone D. had just been gone
44. “ Whose book is on my desk?”. The teacher asked us __________ .
A. whose book is on his desk B. whose book was on his desk
C. whose book on his desk is D. whose book on his desk was
45. She asked me to sit next Mary.
In direct speech, this should be read: “__________”, she said.
A. Please sitting next to Mary. B. Next to Mary, please.
C. Please to sit next to Mary. D. Please sit next to Mary.
46. “Who wrote this letter?”, said the teacher. – The teacher __________
A. asked us who had written that letter. B. asked us who that letter had written.
C. asked us who had written the letter. D. told to us who had written letter.
47. The traffic law requires anyone under 18 __________a motorcycle in the street.
A. don’t ride B. not to ride C. doesn’t ride D. ride not
48. You mustn’t hurry up. If you __________, you will be late.
A. don’t B. won’t C. aren’t D. mustn’t
49. I asked Lan if __________ .
A. she enjoys her music class. B. she will enjoy her music class.
C. did she enjoy her music class. D. she enjoyed her music class.
50. __________? She is about 40 kg.
A. How much is her weight B. How heave is she
C. How much weight is she D. How many kilos is her weight
Choose the best answer to complete these following sentences
1. They couldn’t pass the final____________.
A. exam B. examine C. examining D. examination
2. We have many well ______ teachers here.
A. qualify B. quality C. qualified D. qualification
3. This shirt costs______88,000VND.
A. approximative B. approximately C. approximation D. approximate
4. If you study at the Brighton Language Center- UK, you can live in ______on campus.
A. dormitory B. mobile room C. hotel D. private room
5. I saw your school’s ______in today’s edition of the Vietnam News.
A. advertise B. advertisement C. advertiser D. advertising
6. I can complete a ______ English test if you want.
A. speak B. spoke C. spoken D. speaking
7. She said that she______ learning English with you.
A. like B. liked C. liking D. to like
8. The government supplied the victims______ food and water.
A. to B. with C. on D. for
9. She asked me where I ______from.
A. come B. came C. to come D. coming
10. What aspects of ______ English do you find difficult?
A. study B. studied C. learnt D. learning
11. If you want to attend the course, you______pass the examination.
A. have to B. has to C. had to D. could
12. She______me whether I liked classical music or not.
A. ask B. asks C. asked D. asking
13. He asked me who the editor of this book______.
A. is B. are C. was D. were
14. He told me he______ leave the city the following day.
A. will have to B. would have to C. has to D. had to
15. He wants to know whether I ______ back tomorrow.
A. come B. will come C. would come D. came
16. I wonder why he______ love his family.
A. doesn’t B. don’t C. didn’t D. hasn’t
17. Mary, have you seen our school’s ______in today edition’s of the “ Times”?
A. advertising B. advertisement C. advertiser D. advertise
18. How can we remember all these vocabulary items?- Well, ______.
A. read them in mind B. study them in heart
C. learn them by heart D. tell them by heart
19. Can you tell me the ______ date of the final exam?
A. same B. good C. ready D. exact
20. I’ve read your advertisement in today’s __________of the “ Tuoi Tre”
A. edit B. editor C. editing D. edition
21. In order to attend a higher course of writing you have__________ the English pretest.
A. to get B. to pass C. to finish D. to study
22. He was a strict __________, he asked me a lot of difficult questions.
A. examine B. examining C. examination D. examiner
23. Books in our school library are __________for us to use.
A. available B. willing C. suitable D. worth
24. I’d like __________an advanced course of computing. Is there any available?
A. to go B. to work with C. to attend D. to have
25. If you want any further__________ you can contact their head office.
A. questions B. information C. answer D. responses
26. How can I remember these grammar rules?- Well, try to do all the __________ exercises in this grammar book.
A. studying B. working C. learning D. grammar
27. You should try harder to pass the__________ . It’s the most important one of the term.
A. questionnaire B. final exam C. pretest D. funny quiz
28. If you want to improve your English, you __________ practice it every day.
A. can B. had to C. must D. may
29. I feel sick. I think you __________see the doctor if you want to get well.
A. can B. may C. ought to D. had to
30. If you want to get good marks, you __________ study harder.
A. must B. could C. will D. shall
31. Unless you hurry, we __________ catch the bus.
A. can B. can’t C. must D. mustn’t
32. He asked her __________
A. when she leaves the party. B. when did she leave the party.
C. when she left the party D. when does she leave the party.
33. He said, “ I bought this book yesterday.” -> He told me that __________
A. he bought the book yesterday. B. he had bought the book yesterday
C. he had bought the book the day before D. he bought the book the previous day.
34. He said that we would be met at the airport, but in fact, we__________
A. wouldn’t B. couldn’t C. didn’t D. weren’t
35. He wanted to know __________there
A. how long time I had been B. how long I had been
C. how long time had I been D. how long had I been
36. She asked me what time it was.
In direct speech this should be read: __________
A. She asked, “ What time it is? B. She asked, “ What time it was?”
C. She asked, “ What time is it?” D. She asked, “ What time was it?”
37. “ Whose motorbike did you borrow last night?”, he asked.
In reported speech this should be read: __________
A. He asked me whose motorbike did I borrow last night.
B. He asked me whose motorbike had I borrowed last night.
C. He asked me whose motorbike I had borrowed last night.
D. He asked me whose motorbike I had borrowed the night before.
38. “ Would you like a cup of coffee?”, she asked.
A. She asked if I like a cup of coffee. B. She asked if I would like a cup of coffee.
C. She asked if I liked a cup of coffee. D. She invited me to have a cup of coffee.
39. “ Did you close the windows when you left?”, ha asked.
A. He asked me if I closed the windows when I left.
B. He asked me if I had closed the windows when I left.
C. He asked me if I closed the windows when I had left.
D. He asked me if I had closed the windows when I had left.
40. Are you a school bus driver?- No, not any more, but I __________
A. used to B. used to be C. use to D. use to be
41. “ What are you going to do this weekend?”, she asked
A. She wanted to know what I am going to do that weekend.
B. She wanted to know what I was going to do this weekend.
C. She wanted to know what I were going to do that weekend.
D. She wanted to know what I was going to do that weekend.
42. Can I help you?- Yes, do you know__________?
A. when the bus come B. when the bus comes
C. when the bus came D. when will the bus come
43. She told me that her mother __________ to market when I arrived.
A. just went B. had just gone C. has just gone D. had just been gone
44. “ Whose book is on my desk?”. The teacher asked us __________ .
A. whose book is on his desk B. whose book was on his desk
C. whose book on his desk is D. whose book on his desk was
45. She asked me to sit next Mary.
In direct speech, this should be read: “__________”, she said.
A. Please sitting next to Mary. B. Next to Mary, please.
C. Please to sit next to Mary. D. Please sit next to Mary.
46. “Who wrote this letter?”, said the teacher. – The teacher __________
A. asked us who had written that letter. B. asked us who that letter had written.
C. asked us who had written the letter. D. told to us who had written letter.
47. The traffic law requires anyone under 18 __________a motorcycle in the street.
A. don’t ride B. not to ride C. doesn’t ride D. ride not
48. You mustn’t hurry up. If you __________, you will be late.
A. don’t B. won’t C. aren’t D. mustn’t
49. I asked Lan if __________ .
A. she enjoys her music class. B. she will enjoy her music class.
C. did she enjoy her music class. D. she enjoyed her music class.
50. __________? She is about 40 kg.
A. How much is her weight B. How heave is she
C. How much weight is she D. How many kilos is her weight
Read the passage and then circle the correct answer each question
English is my mother tongue. Besides, I can speak French and Spanish. I studied the two languages when I was at high school. Now, I am still learning Spanish at the University. As for me, mastering a foreign language is not easy. After studying a language, practice is very necessary and useful. Travelling to the country where the target language is spoken is very helpful, but if you cannot speak the language well enough you will certainly have troubles. I also frequently go to the movies, watch television, listen to the radio in the language I am trying to learn. Reading is another good way to learn. Books are good, but I personally think newspapers and magazines are better. However, getting some knowledge of the language is the most important thing. Grammar and vocabulary should be mastered first.
1. How many languages can the writer speak?
A. 1 B. 2 C. 3 D. 4
2. The writer has learnt Spanish _______.
A. in Spain B. at high school C. at university D. B and C
3. Travelling may cause troubles if _______.
A. you cannot speak the language well enough.
B. you can speak the language well enough.
C. you can speak the language badly enough.
D. you can communicate in the target language.
4. Some useful ways to practice your target language are _______.
A. listening to the radio and watching TV in the language.
B. reading books in the language.
C. seeing films in the language.
D. all are correct.
5. According to the write, what should be mastered first?
A. Vocabulary B . Vocabulary and grammar
C. Writing skill D. Reading skill
15. When we saw John, we (stop) __stopped____ to say hello to him.
16. They (offer)__will offer____ you the job if you can use the computer. the paper,
17. While you (read) __were reading___the rapper I was working
18. Arabic (speak) __was spoken__by the people of Syria and Iraq 19. The team was made (practice)__to practice__every day last week.
37. you/.like/ watch/ football matches/ TV?
do you like watching football matches on tv?
38.They/ ask/ him/ continue/ play/ that game
they asked him to continue to play that game
39. wear/ uniforms/ encourage/ students/ proud/ their school
wear uniforms encỏuages students to be proud of their school
40.I/ be/ surprised/ receive/ letter/ Jane/ this morning
i was surprised to receive the letter from jane this morning
30. Everyone felt tired and hungry, ________ they sat down and took a rest
A. because B. although C. so D. but
31. The first courses were offered ________ 1 January 2007.
A. in B. at C. on D. since
32. If you want to ________ your speaking, you should speak English with friends
A. pass B. describe C. express D. improve
33. Students will ________ a two- hour examination at the end of the year
A. take B. make C. do D. come
34. The perfume has been ________ in all the women's magazines
A. recognized B. advertised C. impressed D. read
35. Learning a foreign language also includes learning the ________ of that country
A. reputation B. scenery C. culture D. nature
36. what ________ of learning English do you find most difficult?
A. aspect B. side C. detail D. position
37. We can't hear you clearly. Get ________ the microphone, please.
A. far away B. close to C. next to D. out of
38. ‘ Bill is a late again., ‘ I wish he ________ on time more often.'
A. were B. are C. have been D. will be
39. I'll give you a call if I ________ some help.
A. will need B. need C. would need D. needed
40. I'm sure Tom ________ the examination. He hasn't work hard enough for it
A. hasn't passed B. didn't pass C. doesn't pass D. won't pass
41. I wish the sun ________ shining right now.
A. is B. are C. were D. would
42. I wish Alice ________ sing a couple of songs.
A. would B. will C. can D. is going to
43. If the sky is clear, you can see the stars ________ night.
A. at B. in C. on D. when
44. The first man walked on the moon ________ 21 July 1969.
A. in B. at C. on D. no preposition
45. In Britain people send each other cards ________ Christmas.
A. in B. on C. at D. till
46. If she has too much to do, she must ask someone ________ her.
A. to help B. help C. helping D. helps
47. If she isn't coming tonight, he might ________ next week.
A. to come B. coming C. came D. come.
48. Tom asked her where she ________
A. was going B. goes C. will go D. are going
49. The teacher told us ________
A. not to talk B. not talk C. not talking D. don't talk
50. You must be more polite ________ the customers
A. of B. to C. with D. at
19. Minh is now learning English with a tutor. F
20. The teachers at the Academy of Language are young and inexperienced. F
21. Learners can take courses in the morning. F
22. People who want to attend classes there can phone the school to get information. T
1................a foreign language requires lots of effort and determination.
C: Learning D. Leaner A. To learning B. Learn
2. Your son should ...........more attention in classroom.
A. have B. take C. pay D. get
3. My teacher taught me........... this word
A. what to pronounce B. when to. pronounce C. how to pronounce D. why to pronounce
4. You should............. speaking English as much as possible
A.go B. B. practice C.have D.use
5. Do you have difficulties... learning a foreign language?
A. on B.in C.for D, at
6. He asked me...............I liked watching English TV programs.
A. if B. when C. because D. what
7. If you want to attend the course, you must pass the..............examination.
A. write B. wrote C. writing D. written
8. Are you ready to supply more........ about your study if necessary?
A. news B. information C. report D. content
9. My favorite ...at school was history.
C. theme B. class D. subject A. topic
10. Before you begin the exam paper, always read the....carefully.
A. orders B. instructions, C. rules D. answers
11. If you want to pass the examination, you must study ............
B. enough C. thoroughly D. rather A. hardly
12. It's difficult. in a noisy classroom.
B. study C. studying D. studis A. to study
13. Our teachers used to punish us by making us stay..............after class A. out b. in C. on D. behind A. raise B. rise
14. If you have any question,.........your hand A. raise B. rise C. raising D. rising
15. If you study harder,.......... A. you will get a reward. C. your father will be very happy. D. All are correct. B. you will pass the next exam.
16. If you spend time speaking English every day........... A. you may pass the next oral exam. B. you don't have to worry about the English speaking tests. C. your speaking skill will progress so much. D. All are correct.
17. Lan................ her math exam and had to retake it again. A. failed B. passed C. fell D. succeeded
18. Peter decided not to........for the examination. A. take B. enter C. have D. get
19. We often do somebefore the exams. A. revision B lesson C. leaning D.housework
20. They have learned English. they were ten. D. until D housework C. since A. when