Module-2---Public-holidays-Unit3-Language-in-use.ppt

时间状语从句：在句中充当状语成分的句子while ,before ,when ,as soon as ,since ,after 一、时间状语从句的用法： 1. 时间状语从句常由 when, while, till, until, before, after, since, as soon as 等引起，如： I went to bed after I had finished my homework.(在……后) He has worked in the factory since it opened in 1992.(从……起) I’ll give him the book as soon as I see him.(一……就……) 注意 1、when 和while区别 when后面的动词可以是延续性动词，也可以是非延续性动词。 while意思是“当……的时候”，由它引起的从句中必须用动词be、延续性动词或动词的进行时态，而不可用终止性动词。如： I was walking in the street when the UFO landed. He came to see me while I was having dinner. while 还可以表示两者同时进行。 I was doing my homework while my parents were watching TV. 2.until和till 均可引起时间状语从句，表示“直到某时为止”，当主句动词为延续性动词时常用肯定式，当主句动词为终止性动词时常用否定式，如： He kept working until (till) it began to rain. He didn’t go to bed until (till) he finished his homework. (他直到做完作业才上床睡觉。) 区别： till和until用作连词或介词均可表示“直到……为止”，但放在句首时一般不用till而用until，如： Until then, I knew nothing about it. Until it began to rain, they kept on working in the field. 巩固练习 1. He was so tired that he fell asleep _____ he went to bed. (1) A. as if B. even though C. ever since D. as soon as 2. John fell asleep _____ he was listening to music. (10) A. after B. before C. while D. as soon as 3. “It’s late. I must go.” “It’s raining outside. Don’t leave _____ the rain stops.” (14) A. when B. since C. while D. until 4. I left my umbrella in my room. Could you wait _____ I go back to get it? (17) A. when B. if C. so D. since 5. He was riding to school _____ he was hit by a car this morning. (19) A. while B. when C. as D. so 6. I arrived at the airport _____ the plane had taken off. (20) A. after B. while C. when D. before 7. I was cooking in the kitchen _____ there was a knock on the door. (26) A. while B. because C. until D. when 8. I _____ until he came back. (29) A. didn’t wait B. waited C. won’t leave D. left 9. Dick climbed up a tree _____ he saw a bear. (31) A. while