时间状语从句和原因状语从句

时间状语从句和原因状语从句
【归纳1】引导时间状语从句的连词主要有when, while, as, before, after, since, till
until, as soon as, once等，本期主要讲解when, while和as引导时间状
语从句的用法。
连词 用法 例句
表示“当……的时候”，从句中既可用
He waved when he saw her.
延续性动词也可用非延续性动词。
从句的动作既可和主句的动作同时
发生又可在主句动 作之前或之后发
生。
when
It was raining when we arrived.
When I met the Gills, I had been
gardening for nearly ten years.
用于be doing sth. when ...结构中，表
I was preparing lunch in the kitchen
示“正在做某事时突然……”。
用于be about to do sth. when ...结构
when the power was off.
We were about to have dinner when
中，表示“正要做某事时突然……”。
someone knocked at the door.
用于had just hardly + 动词-ed形式
+ when ...结构中，表示“刚做完某事
突然……”。
表示“在……期间，与……同时”，从
while
句的谓语动词必须是延续性动词，
强调主句动作在从句动作发生的过
程中发生或两动作同时进行。
I had just hardly fallen asleep
when the phone rang.
Sam fell asleep while he was doing
his homework.
You can go swimming while I’m
having lunch.
表示“随着，一边……一边……”，侧
As time passed, things seemed to
as
重主句和从句两个动作同时发生或
主句动作随从句动作的变化而变
化。
She cried as she watched the movie.
get worse.

【归纳2】常见的引导原因状语从句的连词主要有：because, since, as, now that
等。
连词 用法
语气最强，表示直接原因，
because
常用来回答why引出的问
题；通常放在主句之后，不
能与so连用。
—Because I was ill.
Since you are unable to answer,
since now
that
语气较弱，强调已知的事实，
常放在主句之前，译为“既
然”。
maybe we should ask someone
else.
Now that you have finished your
work, you’d better have a rest.
as
较口语化，常放在主句之前，
As it was getting late, I turned
表示明显的原因和理由。
around to start for home.
—Why didn’t you come to school
yesterday?
例句
I did it because he told me to.
注意：for也可表示原因，连接两个分句，但for后面的分句只是 对前面的分句补
充说明理由或推断原因。for引导的分句只能放在句子后部，与前一分句以逗号
隔开。如：
I cannot tell whether she is old or young, for I have never seen her.
【即学即练1】用when, while或as填空。
1. Kevin gets more attractive ________ he gets older.
2. I’ll phone you again ________ I get home.
3. Could you take care of the children ________ I cook lunch?
【即学即练2】用because, now that, since, as或for填空。

1. The game was called off ________ it rained.
2. ________ you’ve passed your test you can drive on your own.
3. —Why can’t I go?
—________ you’re not old enough.
4. I believed her, ________ surely she would not lie to me.
答案
【即学即练1】
1. when 2. when 3. while when
【即学即练2】
1. because 2. Now that Since As 3. Because

4. for