A. since B. when
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C. as D. while
2) ______ I accept that he is not perfect, I do
actually like the person.
A. While B. Since C. Before D. Unless
2. 连接词while 的用法小结
2) while 只表“时间段” (=during the time that), 从句中 动词只限于持续性动词，它有时含对照之意，表 “然”而
i.e.(1) He fell asleep while he was studying his
grammar book.
3) as用法与when 相似，但它侧重动作的同时性，表 “一边 ...一边 ...”，还表“随着”
at the time that), 从句中动
词既可是终止性的，
也可是持续性的，
还可表“正在这时”
i.e. (1). When I arrived there, they were watching
TV.
(2). When I was young, I liked singing and
dancing.
A. why B. where C. when D. while
1) The cost of living in Glasgow is among the
lowest in Britain, ______ the quality of life
is probably one of the highest.
--- Yes. It was not yet eight o ' clock ____
he arrived home.
A. before B. when C. that
D. until
3. He was about halfway through his meal
______ a familiar voice came to his ears.
1)while 引导的动作 必须是持续性的，侧重主句动作
和从句动作相对比。如：
Please don ' t talk so loud while others are
working.
2)while 作为并列连词，意为“而，却”，表示对比。
3)while 可表示尽管，相当于 although 。
While I was waiting for Tom, three buses went
我正准备告诉他那个秘密，这时有人拍了拍我的肩膀。
I was about to tell him the secret when someone
patted me on the shoulder.
I had hardly got home when it began to rain. Hardly had I got home when it began to rain.
Unit 4 Grammar (1)
时间状语从句：
引导时间状语从句的连词有：
when, while, as, before, after, till, until, since, as soon as, the moment, immediately, every time, next time, the first time, once 等。
1. He transplanted the little tree to the garden
______ it was the best time for it.
A. where B. when C. that D. until
2. --- Did Jack come back early last night?
when, while, as 表“当...时”的异同 ：
相同点: 当从句的谓语是延续性动词时，三者常
可互换
i.e. When/While/As we were still laughing, the teacher came in.
不同点: 1) when 既表“时间段”又表“时间
点”(=during or
by.
I do every single bit of housework,
while my
husband Bob just does the dishes now and
then.
While modeling business is by no means easy
to get into, the good model will always be in
demand.
when/while doing: 1)When /While I was looking through the paper, I noticed a few grammatical mistakes When /While looking through the paper,I noticed a few grammatical mistakes. 2)While he was wandering through the square, he caught sight of a snake-charmer While wandering through the square,he caught sight of a snake-charmer when/while done When we were taken round the city, we were impressed by the city's new look. When taken round the city,we were impressed by the city's new look.
i.e.(1) They talked as they walked. (2) As time goes by, we get wiser.
1. when --- 正在… 的时候，突然 …
I was walking along the street when I met him. One evening, little Hans was sitting near the fire when he heard a loud knock at the door. I was about to fall asleep when my sister came in. He had just got back home when the telephone rang.