时间状语从句

状语从句
一、什么是状语、状语从句？
状语：是用来修饰动词、形容词、副词或全句用的。

eg：He works hard! （他努力工作）中的hard。

状语的位置：
1）修饰形容词或副词的状语放在被修饰语之前。

eg：The Summer Palace is very beautiful.颐和园非常美丽。

（very 为状语，修饰形容词beautiful，放在beautiful 之前）。

2）修饰动词的状语有的放在动词前，有的放在动词之后。

如果动词有宾语，状语一般须放在宾语之后。

eg：I He often came here to see me.他经常到这里来看我。

（often 为状语，修饰动词came，放在前面）。

I know him well.我十分了解他。

（well为状语，修饰动词know，放在know 之后）。

状语从句：用一个句子（从句）来作另一个句子（主句）的状语，用作状语的句子就叫作状语从句。

作什么样的状语就叫什么类型的状语从句。

例如：条件状语从句就是用一个句子来作条件状语。

二、状语从句的分类。

（1）时间状语从句
凡是从句都必须有引导词，引导时间状语从句的词有when，before，after，until，as soon as，while 等，具体用法如下：
1. when 意为“当……时”，引导时间状语从句，表示主句的动作和从句的动作同时或先后发生。

eg: I feel very happy when you come to see me.
When you are crossing the street，you must be careful.
when引导的时间状语从句，when的从句可以用延续性动词，也可以用瞬间动词。

eg：He was working at the table when I went in. 。

Someone knocked at the door when I was sleeping.
I will visit my good friend when I have time.
注：when也可以作并列连词，表示一个动词正在进行的时候，突然间发生了另外一件事。

eg: I was fishing by the river，when someone called for help.
We were working in the chemistry lab，when the lights went out.
2. before 意为“在……之前”，引导时间状语从句时，表示主句的动作发生在从句的动作之前。

eg: We cleaned the classroom before we left school yesterday.
He had been a cook before he went to college .
after 意为“在……之后”，引导时间状语从句时，表示主句的动作发生在从句的动作之后。

eg: After you use plastic bags，you mustn't throw them about.
He called me after he had finished his work.
注：若主句和从句两个动作发生的先后顺序十分接近，那么也可以不用完成时态，如上面的第二句可改成：He called me after he finished his work.
3. since引导的时间状语从句，译为“自从……”，主句常用现在完成时，从句常用一般过去时。

eg: I have taught English, since I came to Shenzhen.
注：常用句型：It is +时间段+since从句译为：自从……有多长时间了。

eg. It is six years since she graduated from the university.
4. until 意为“直到……时”，引导时间状语从句时，表示主句的动作发生在从句的动作之前。

当主句的谓语动词是持续性动词时，主句常用肯定形式；当主句的谓语动词是非持续性动词时，从句常用否定形式，not…until…意为“直到……才……”，这时的until可以用before 来替换。

eg：I'll stay here until you come back.
我会呆在这里，直到你回来。

(stay表示的动作可以持续)
He didn't go to bed until he finished his homework.
他直到做完作业才睡觉。

（go to bed 表示的动作不能持续）
5. as soon as 意为“一……就……”，表示从句的动作一发生，主句的动作马上就发生。

eg：I'll tell him about it as soon as he comes back.
6. while引导的时间状语从句，常译为“与……同时，在……期间”，while的从句中常用延续性动词或表示状态的词。

eg. They rushed in while we were discussing problems.
Father was cleaning the car while I was playing computer games.
注：while也可以作并列连词，表转折的关系，相当于but，译为“然而”。

eg. I like listening to music，while my brother likes doing sports.
7. till和until引导的时间状语从句，译为“直到……为止”，not …till / until引导的时间状语从句，译为“直到……才”。

前者强调主句动作的结束，用延续性动词，后者强调主句动作的开始，用瞬间动词。

eg. I will wait for my friend until / till he comes. 我要一直等到我朋友来。

We won't start our discussion until / till he comes.
我们要等到他来了，再开始我们的讨论。