状语从句精讲PPT课件

1．while引导的时间状语从句的谓语动词必须是 可延续的， 而when引导的时间状语从句的谓语 动词是可延续的，也 可以是表短暂性动作的动词。 When/While he was eating his breakfast, he heard the doorbell ring.
When I stopped my car, a man came up to me.
句型It will be/was＋一段时间＋before…“还 要过多久才……”
had just done sth
I was walking along the street , when I met him
I was about to fall asleep when my sister came in.
3. 还可以表示原因“既然”，相当于since; considering
When/While/As I was walking down the street, I came across an old friend of mine.
4.从句动作发生在主句动作之前时，只能用 when引导这个从句，不可用as或while。
When you have finished your work, you may have a rest.
3. while可表示尽管，相当于although。
※while 含义：
While I was walking down the street, I came across an old friend. ( while =__w_h_e_n__)
He likes pop music, while I am fond of folk
music. ( while =_b_u__t ___)
While I really don’t like art, I find his work impressive. (while=__a_lt_h_o_u_g_h___)
While there is life there is hope. (while=___a_s_l_o_n_g_a_s_____)
状语从句精讲
在复合句中由从句表示的状语称作 状语从句，它可以用来修饰谓语或 是整个句子。
状语从句
时间状语从句
地点状语从句
状
原因状语从句
语
目的状语从句
从
结果状语从句
句
条件状语从句
方式状语从句
让步状语从句
比较状语从句
时间状语从句
引导时间状语从句的连词有：
when, while, as, the moment, before, after, till, until, since, as soon as 等。
Please don’t talk so loud while others are working.
2. while作为并列连词，意为“而，却”，侧重 主句动作和从句动作相对比。
We are cleaning the classroom while they are playing the football.
When the children had gone to bed, she began to prepare her lessons.
We had sailed four days and four nights before we
saw land. “……才”
We hadn’t run a mile before he felt tired.
1 when引导的时间状语从句的谓语动词 可以是延续性动词
也可以是表短暂性动作的动词(非延续性)。
When the film ended, the people went back.
When I lived there, I used to go to the seashore.
2 when表示 “就在这时” 在下列结构中，表示某件 事正在发生或刚刚发生，另一动作同时发生。 be about to do… when… be doing… when… had done… when…
I will tell him when he comes back.
连接词when的用法小结
1. when引导的时间状语从句的谓语动词
可以是可延续
也可以是表短暂性动作的动词(非延续性)。
如When the film ended, the people went back.
When I lived there, I used to go to the seashore.
We were about to start when it began to rain.
I was playing computer games when mom came in.
1. while引导的动作必须是持续性的，在……期间， 往往指一段时间。如： While we were talking, he came in.
(不可延续，短暂性动词，只可以用when，不 可用while)
2．表示“随着……”，连词用as，不用when 或while。
As the day went on, the weather got worse.
3如果主句表示的是短暂动作，而从句用延续 性动作的进行时态表示在一段时间内正在进行 的动作时，when, while 与as 可互换使用。
2. 可用作并列连词，其意义为“那时，这时”，相当于
and at this/that time。常用于下列句式：
(刚要……这时突然……) 记忆
Sb. was doing something
was about to do sth
+ when…来自was on the point of doing sth.
“不到……就”
Please write it down before you forget it.
“趁……”
Before I could get in a word, he had measured me.
“还没来得及”
Before从句中谓语不用否定式
Before they reached the station, the train had gone.