河南专升本英语时间状语从句

　　2021年河南专升本考试时间还不确定，以下是库课李老师给考生整理的河南专升本英语时间状语从句，考生可在考前认真查看。

　　河南专升本英语时间状语从句

　　时间状语从句

　　1、 when, while, as 和 whenever when 表时间点，时间段

　　while 表时间段;有“而”的意思

　　as “当……”,“一边……一边”，“随着……” whenever 每当，无论什么时候

　　Eg: It is cold when it snows.

　　While there is life, there is hope.

　　While we were speaking, he was reading newspaper.

　　Just as Mrs Richards was entering the dinning-room, there was a knock on the front door

　　如果主句表示的是短暂动作，而从句用延续性动词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。如：

　　When/While/As I was walking down the street，I came across an old friend of mine. 2 、 before/ after

　　Eg: It will be five years before we meet again.五年之后我们才能见面。After you think it over, please let me know what you decide.

　　After her husband had gone to work, she sent her children to school.

　　3 、 until, till, not...until

　　肯定句：主句的谓语是延续性动词，主从句均为肯定式，意为“某动作一直持续到某时间点才停止” Eg: Please wait until I come back.等我回来。

　　否定句：主句的谓语是非延续性动作，从句为肯定式，意为“某动作一直到时间点才开始” Eg: He won’t go to bed till/until she returns.

　　Till 不可以用在句首，而 until 可以

　　Eg: Until you told me I had no idea of it.

　　4、since 从句谓语动词多用于一般过去时态，主句用现在完成时态或现在完成进行时态

　　Eg She has been working in this factory since she left school.

　　I have written to Alice four times since I came here.

　　It is +一段时间+since 从句的句型中，时间计算一律从 since 从句动作完成或状态结束时算

　　Eg: It is three years since the war broke out. 战争爆发以来，有三年了。

　　It is three years since she was in our class.她离开我们班有三年了。

　　5、by the time 到……时候;到……之前(从句用一般过去时，主句用过去完成时) Eg: By the time I got outside, the bus had already left.

　　2021年准备参加河南专升本考试的考生一定要在考前好好复习，2021年河南专升本视频课程已经更新，考生可登录库课网校进行观看。