1. “主将从现”原则
即若主句为一般将来时，时间和条件状语从句通常要用一般现在时表示将来，而不能直接使用将来时态。如：
I’ll give her the telex when she comes. 她来时把电传交给她。
I’ll return the book as soon as I have read it. 这书一看完我就送还。
He’ll have four years at university after he leaves school. 他中学毕业后要上四年大学。
2. since与完成时
since 引导时间状语从句时，其主句通常要用现在完成时，有时也用现在完成进行时。如：
She has had another baby since I saw her last. 从上次我见到她以来，她又生了一个孩子。
He has grown an inch since I saw him. 我上次见到他以后他已长高了一英寸。
注：当主句为“It + be + 一段时间”时，则通常用一般现在时代替现在完成时。如：It’s more than three years now since I sa w her last. 我们已有三年多没见面了。
3. 特定句式的时态
由no sooner. . . than, hardly [scarcely]…when引出的时间状语从句，其主句通常用过去完成时，从句通常用一般过去时。如：
Hardly had he arrived when she started complaining. 他刚到她就抱怨起来。
No sooner had he gone to sleep than the telephone rang. 他刚睡着电话铃就响了。
We had no sooner set out than a thunderstorm broke. 我们刚出发就下起一阵雷暴。
No sooner had she agreed to marry him than she started to have terrible dou bts. 她刚同意嫁给他她就开始产生可怕的疑虑。
状语从句的时态特点
一般情况下，时间和条件状语从句的谓语动词一般用“一般现在时”表示“一般将来时”，用“现在完成时”表示“将来完成时”。例如：
I will call you as soon as I arrive in Beijing. 我一到北京就给你打电话。（这是由as soon as引导的时间状语从句，从句中的谓语动词arrive是一般现在时，表示一般将来时，决不可用will arrive）
As soon as I have finished this work, I will go home. 我一完成此工作，就回家。（从句中的谓语动词用现在完成时have finished，表示将来完成时,决不可用will have finished）
If he comes back, please let me know.如果他回来了，请通知我。（从句中的谓语动词用comes back,表示一般将来时，决不可用will come back）
状语从句讲解和练习
状语修饰动词、形容词、副词或整个句子。通常由副词、介词短语、动
词不定式、分词和从句等担当。例如：
1. Naturally , our grandparents were pleased to get our phone call .
(副词)
2. We worked hard , from sunrise to sunset . (介词状短语)
3. To help my disabled aunt , I spend an hour working in her house
every day . (不定式)
4. Seen from a distance , the farmhouse looked deserted . (过去
分词)
5. I know how to light a camp fire because I had done it before .
（原因状语从句）
状语的位置比较灵活，可以位于句首、句末或句中。enough用作状语修
饰形容词和副词时必须后置。
状语从句主要用来修饰主句或主句的谓语。一般可分为九大类，分别表示时间、地点、原因、目的、结果、条件、让步、比较和方式。尽管种类较多，但由于状语从句与汉语结构和用法相似，所以理解和掌握它并不难。状语从句的关键是要掌握引导不同状语从句的常用连接词
和特殊的连接词即考点。现分别列举如下:
1．时间状语从句
常用引导词：when, as, while, as soon as, before, after, since ,
till, until
特殊引导词：the minute, the moment, the second, every time, the day，the instant, immediately , directly, no sooner … than,
hardly …when, scarcely … when
I didn’t realize how special my mother was until I became an adult.
While John was watching TV, his wife was cooking.
The children ran away from the orchard(果园) the moment they saw
the guard.
No sooner had I arrived home than it began to rain.
Every time I listen to your advice, I get into trouble.
