语动词多用一般过去时，而主句中谓语动词多用现在完成时或现在完成进行时。

　　We have never met since we graduated from the college.自从我们大学毕业后就再也没有见过面。

　　It is/has been five years since I last saw him.

　　我已经五年没有见他了。

　　3. till/until引导时间状语从句时，主句为肯定句，其谓语动词是延续性动词，表示"直到......为止"；主句为否定句，其谓语动词是终止性动词，表示"直到......才"。

　　He waited until/till his mother came back.

　　他一直等到他妈妈回来。

　　I didn't go to bed until/till I finished my homework.直到做完作业我才上床睡觉。

　　[名师点津]　

　　(1)在not...until...结构中，当not until...置于句首时，主句要部分倒装。

　　(2)当not...until...结构用于强调句型时，句子结构为：It is/was not until...that...

　　4．as soon as, the moment, the minute, immediately，directly等引导的时间状语从句，表示"一......就......"。

　　The moment/ Immediately/ As soon as I heard the voice, I knew my father was coming.

　　一听到声音，我就知道父亲回来了。

　　[名师点津]　

　　no sooner...than..., hardly...when...可以表示"一......就......"，但要注意以下两点：

　　(1)当hardly, no sooner置于句首时，其后的句子用部分倒装；

　　(2)hardly和no sooner后的句子常用过去完成时，when和than后的句子常用一般过去时。

　　We had no sooner arrived at the station than the train left.

　　＝No sooner had we arrived at the station than the train left.

　　我们一到火车站，火车就开了。

5. 短语every time, each time, next time, the first time, by the time