when while since until的区别?
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发布时间：2022-08-15 19:38
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热心网友
时间：2023-09-19 03:55
(2)while.①在…的时候。注意while从句须用延续性动词。Eg. While I was sweeping the floor, Mr. Zhou walked in. eg. _______she left her hometown, it was snowing hard. A. When B. while C. after
②while可作并列连词，表示比较或对比。意为“而/却/可是”
eg. Mother often takes a bus to work______Father usually goes by car.
Eg. We Chinese like using chopsticks______westerners prefer knives and forks.
A.when B. while C. because D. since E. that
(3) ①before.在…之前。主句谓语动词先于从句的谓语动作之前。②before 还有其它的意思“还要过多少时间/过了多少时间才…”
eg. He covered not more than 5 miles______it began to rain heavily.
Eg. Ten years had passed______he realized he hadn’t learned much.
Eg. It won’t be long_____Mother returns home.
Eg. The boy was run over by the train_____she could save him.
A. after B. before C. when D. since E. until
(4)till/until. “直到…”后面不能接地点名词。①可作介词，后跟时间点。②也可以作连词，引导时间状语从句。③till 和until 可互换，但是从句位于句首时只能用until. ④not…until. “直到…才…”。如果主句的谓语动词为非延续性动词，主句应当用否定式。
eg. _____the sunset, they didn’t leave their workplace.(till/until)
eg. The bus stopped until it pulled in.(改错)
注：not until 置于句首时引起倒装， 其结构为：not until…+ 主句部分倒装。
（5）since. 自从…以来。①since + 时间点 ②since + 时间状语从句 ③含since 引导的时间状语从句的复合句，主句用现在完成时，since从句用一般过去时。④注意以下句式： It is/has been + 时间段 + since 从句. 如果since 从句的谓语动词为非延续性动词，该句式表示这动作或状态已持续了多久；如果since从句的谓语动词为延续性动词，则表示该动作已终止了多久。Eg. It is three years since he began to teach in our school.他在我们学校已经教了三年书。Eg. It is three years since the Greens lived here.格林夫妇三年前从这里搬走了。⑤since 与before的区别：A. since 的主句用现在完成时，而since从句用一般过去时。Eg. The Grees have lived here since they move to this little town. B. before 用法：主句（一般将来时） + before +从句（一般现在时）；主句（过去时态） + before + 从句（一般过去时）
eg. It will be three months before he comes back. 还有三个月他才会回来。
Eg. The boy was run over before she could rush to save him. 他还未来得及冲过去救那个还子，车子就已经从孩子身上碾过了
热心网友
时间：2023-09-19 03:56
conj. 当...时
pron.&ad. 什么时候
例句:
The Queen's last visit was in May, when she opened the new hospital.
女王上次来访是在五月份，她那时主持了这座医院的落成典礼。
How can they learn anything when they spend all their spare time watching television?
他们把所有的空闲时间都用来看电视了，还能学什麽东西呢？
It was the sort of morning when everything goes wrong.
那天上午就是那样，事事不顺心。
while [(h)wail]
conj. 当...的时候
n.&a. 一会儿
v. 消磨
例句:
I lived in a hostel while I was a student.
我求学期间住在青年招待所里。
She worked in a bank for a while before studying law.
她学法律之前在银行工作过一段时间。
While Mary was writing a letter, the children were playing outside.
玛丽写信时，孩子们在外面玩耍。
since [sins]
ad. 后来
conj. 既然,因为
prep. 自从
例句:
She moved to London last May and has since got a job on a newspaper.
她去年五月到伦敦，此後一直在报社工作。
It was the first time I'd won since I'd learnt to play chess.
自从我学会下国际象棋以来，这是我第一次赢。
How long is it since we visited your mother?
自从我们看望你母亲以来到现在有多长时间了？
until [�0�5n'til, �0�5n'til]
prep.&conj. 直到...为止
例句:
She was a bank clerk until the war, when she trained as a nurse.
她战前是个银行职员，战时受训当了*。
He lived in California until he was twenty.
他在加里弗尼亚一直住到20岁.
I didn't wake up until I heard the alarm clock.
直到听到闹钟的铃声我才醒来。
热心网友
时间：2023-09-19 03:56
热心网友
时间：2023-09-19 03:57
while当……时，前接现在进行时，后接过去进行时
since自从
until直到
