高三语法复习：
状语从句
1.时间状语从句。
引导时间状语从句的有：when, while, as, before, after, since, till, until, as soon as, no sooner…than…, hardly…when…等。
（1） When, while和 as
When既可引导一个持续动作，也可引导一个短暂动作，可用与主句和从句动作同时发生或从句动作先于主句动作。while引导的从句中谓语动词必须是能够延续的动词，强调主句和从句动作的同时发生，往往侧重动作的持续性和对比性。如：While I was sitting there, he told me an interesting story．as用于引导“在某行为的继续中发生某事”的“继续之行为”，所以多与过去进行时连用。并常用来表示两种发展变化中的情况。
When they came home, I was cooking dinner.
She watched TV while (she was) eating.
As I was walking down the street, an American asked me for directions to the nearest station.
As the day went on, the weather got worse.
(2) 时间状语从句还有几个特殊的引导词。
如：every time, each time, next time, the day, the year, the minute, the moment 和副词immediately, directly, instantly等.
a.Every time I saw him, I would like to listen to his songs.
b.I came to the house the moment he was about to leave.
c.I recognized her the minute I saw her.
d. He left Europe the year World War II broke out.
e. My sister came directly(=as soon as) she got my message.
f. The machine will start instantly you press the button.
(3) since 和 before 的用法异同。
It is/ has been + some time+ since+ sb did sth.
It was / is / will be + some time+ before sb did/ do sth
It is just a week since we arrived here.
It’s a long time since I met you last.
How long is it since you were in Ningbo ?
It was years before I came back from abroad. It will be five years before we meet again.
It wasn’t long before he came back..
since 其后的动词不同,起算的时间也不同.
since + 瞬间动词过去式 (从该动作发生时算起)
since + 持续性动词的过去式 ( 从该动作结束时算起)
He worked very hard since he entered the factory.
We haven’t seen each other since I worked in the factory.
(从我不在厂工作以来……)
She has never been to visit me since I was ill. (病愈以来)
(4)till& until意义相同，多数情况下可换用，但用以强调，句首多用until；在强调结构或与not连用时多用until。例如：Nothing can be done till/ until the boss returns.
I waited for him until he came back.
He didn’t go to bed until he had finished the work.
Until we know the facts, we can’t do anything about it.
(5) no sooner…than, hardly…when和scarcely… before相当于as soon as之意, 其引导的从句中谓语动词要用 had done。当 hardly, scarcely和 no sooner置于句首时,语气较强, 主句的谓语要部分倒装. 例如:
We had hardly begun when we were told to stop.
Hardly had we begun when we were told to stop.
The spy had no sooner returned home than he was told to go to another country.
No sooner had the spy returned home than he was told to go to another country.
2. 地点状语从句由where或 wherever引导，在主句前，后均可．
where 表特指，wherever表泛指
I found the books where I left them.
Make a mark where you have any questions.
Wherever he happens to be, John can make himself at home.
(1) 地点状语从句在句首时常兼有抽象条件意味。如：
Where there’s a will, there’s a way.
Wherever there’s plenty of sun and rain, the fields are green.
(2) where引导的状语从句和定语从句的区别。Where引导地点状语从句直接修饰动词,而在定语从句中 where作为关系副词要跟在表示地点的先行词后面。 如：
Go back where you came from
Go back to the village where you came from.
Bamboo grows best where it’s wet and rainy.
Bamboo grows best in places where it’s wet and rainy.
3. 原因状语从句because, since, as, for,
because表直接的原因,语气最强.
since “既然”:一般放在句首,表已知的原因,全句重在交代结果,语气比because弱.
as 放在句首或句末,说明因果关系,语气较弱,重点在主句,译作“由于”for表间接原因，用来补述内容．放在主句后.语气最弱.
Since (As) it was raining, you ‘d better take a taxi.
Because he is ill, he is absent today.
He must be ill, for he is absent today.
As he is from the south, he is unaccustomed to the dry weather in Beijing.
在强调句型中,引导从句只能用because, 不能用 since或as.
It was because he was ill that he didn’t go with us.
4. 条件状语从句
引导词: if, unless, so/ as long as用一般现在时表示一般将来时
In case anything important happens, please call me up.
I’ll lend it to you as long as you handle it with care.
if only(要是…就好了; 但愿) 常表示愿望或一未实现的条件,尤用于感叹句.
If only he arrives in time!
If only I had met him earlier!
If only it would stop raining!
on condition(that)=provided (that) =providing (that) ( 假若; 倘使)
supposing (that) =if
You can go swimming on condition that you don’t go too far from the river bank.
I’ll go providing my wages are paid.
Supposing it rains tomorrow, what shall we do?
*在条件状语从句中,如果条件状语从句的主语同主句主语一致或是无人称代词, 从句的谓语动词或助动词 be, 可将从句的主语和动词 be一起省略.
If (it is) necessary, I’ll go with him.
If (it is) important, I’ll write this article.
目的和结果状语从句
目的:so that… in order that… ( 情态动词)
结果: so that, so/ such… thatHe studied even harder so that he might catch up with the top students in a possible short period.
He studied even harder so that he caught up with the other students.
He made a wrong decision, so that half of his lifetime was wasted.There are so many people in the room that we could’t get in.
方式状语从句
方式状语从句放在主句之后，用as, just as, as if, as though 等引导。
注意:
1) as 表行为方式
2) as if 引导的从句表示与事实相反或不可能实现时,从句用虚拟语气。
比较状语从句
引导词: than, as… as,
the more… the more…He didn’t do as much as he had
promised.
Now we can produce much more
steel than Japan.
The higher you stand, The farther you will see.
注意被比较的内容应一致
The weather here is hotter than that( = the weather) in your hometown.The girls in your class are more active than those in our class.
责任编辑：李芳芳