时间状语从句.doc

时间状语从句
（1） when, while, as
when引导时间状语从句可指时间的一点，从句的谓语用瞬间动词；也可指一段时间，从句用延续性动词。
When I was walking down the street, I saw some policemen.
When they heard the news, they were very surprised.
While: 从句用延续性动词，表示一段时间
Don’t talk to others while others are working.
as: 随着…
As you grow older, you’ll know better about yourself.
练习：Because of the heavy traffic, it was already time for lunch break ___ she got to her office.
A. since B. that C. when D. until
(2)一…就…： as soon as, no sooner …than…，hardly…when…
注意no sooner …than…，hardly…when…这一结构的时态搭配，no sooner与hardly 引导的主句谓语用过去完成时，而than 与when的从句中的谓语用一般过去时。此外，当把no sooner 和hardly放在句首时，句子应用倒装语序。
Hardly had he arrived when it began to rain. No sooner had she gone to sleep than the telephone rang once more.
(3)一些表示时间的名词词组，如the moment, the second, the minute, each time, the first time, the year等，也可用于引导时间状语从句。
Each time he came, he would bring us a lot of flowers. The moment I saw him, I thought of his father. The first time he went to Shanghai, he visited his former teacher.
(4)副词instantly, immediately, directly 也可作连词用，意为一…就…。
The young lady rushed into the room immediately she heard the noise.
I recognized her instantly I saw her.
(5)until/till 主句的谓语动词如果是延续的，用肯定式，意为一直到…；如果是非延续性的，要用否定式，意为直到…才…。
I waited at the school gate until he came. I didn’t leave until he came back.
(6)before：…才……， …就，还没来得及…
We had sailed four days before we saw land. Before they reached the station, the train had gone.
Before I could get in a word, he had measured me.
It will be +一段时间+ before sb does sth多久之后才会…
It will be half a year before I come back. It won’t be long before we meet again.
(7)since: 从句用一般过去时，主句用现在完成时。
I have written home four times since I came here.
It is/ has been+一段时间+since 从句 自从…有多久了
It is three years since I stopped smoking.
2.条件状语从句
引导词有：if, unless, as long as, once, in case, on condition that, supposing that, providing that, provided that, 在条件状语从句中，用一般现在时代替一般将来时，用一般过去时代替过去将来时。
If it snows tomorrow, we will build a snowman. You will be late again unless you hurry.
As long as you promise to come, I will wait for you.
Providing/ Provided that you promise not to tell anyone else, I will explain the secret.
In case it rains, do not wait for me. I will do it on condition that you help me.
3.让步状语从句
引导词有：though, although, even though/if, as, whether…or not…，whatever, whichever, whoever, whomever, whenever, wherever, however等。
（1） although, though, as
as: 引导让步状语从句时，要倒装，adj./adv./ n. +as +主语+谓语
Pop star as she is, she still needs to improve. Young as/though she is, she knows so much about life.
Bravely as/though they fought, they had no chance of winning. Child as/though he is, he can speak three languages.
Though, although: although 引导让步状语从句，从句不倒装；though引导让步状语从句，从句可以倒装，也可以不倒装。
Although/ though she works very hard, she makes very slow progress.
(2).wh-ever引导让步状语从句时，这类词在引导让步状语从句时可换成no matter +相应的wh-词。
Whenever I am unhappy (=No matter when I am unhappy), it is my friend who cheers me up.
I’ll wait for you however late it is(=no matter how late it is).
Whatever he is wearing (=no matter what he is wearing), you must respect him.
(3)whether …or…和whether …or not也可引导让步状语从句。
All the nations should be equal, whether they are strong or not.
Sports will be important to people, whether they are men or women, old or young.