largest fish I have ever seen. It is / was the first time +that-clause 的句型中，从句要

　　用完成时。

　　2017 昆明小升初家长群 106422652

　　2017 昆明小升初家长群 106422652

　　注意：非延续性动词的否定形式可以与表示延续时间的状语连用。即动作不发生的状态是

　　可以持续的。

　　I have received his letter for a month.

　　I haven t received his letter for almost a month.

　　3  比较since和for

　　Since 用来说明动作起始时间，for用来说明动作延续时间长度。

　　I have lived here for more than twenty years.

　　I have lived here since I was born..

　　My aunt has worked in a clinic since 1949.

　　Some new oilfields have been opened up since 1976.

　　I have known Xiao Li since she was a little girl.

　　My brother has been in the Youth League for two years.

　　I have not heard from my uncle for a long time.

　　注意：并非有for 作为时间状语的句子都用现在完成时。

　　I worked here for more than twenty years.

　　I have worked here for many years.

　　小窍门： 当现在完成时+一段时间，这一结构中，我们用下面的公式转化，很容易就能排

　　除非延续动词在完成时中的误使。

　　2017 昆明小升初家长群 106422652

　　2017 昆明小升初家长群 106422652

　　1) Tom has studied Russian for three years.

　　= Tom began to study Russian three years ago, and is still studying it now.

　　2) Harry has got married for six years.

　　= Harry began to get married six years ago, and is still getting married now.

　　显然，第二句不对，它应改为 Harry got married six years ago. 或 Harry has been

　　married for six years.

　　4  since的四种用法

　　1) since +过去一个时间点 。

　　I have been here since 1989.

　　2) since +一段时间+ ago

　　I have been here since five months ago.

　　3) since +从句

　　Great changes have taken place since you left.

　　Considerable time has elapsed since we have been here.

　　4) It is +一段时间+ since从句

　　It is two years since I became a postgraduate student.

　　5 延续动词与瞬间动词

　　2017 昆明小升初家长群 106422652

　　2017 昆明小升初家长群 106422652

　　1) 用于完成时的区别

　　延续动词表示经验、经历; 瞬间动词表示行为的结 果，不能与表示段的时间状

　　语连用。

　　He has completed the work. 他已完成了那项工作。

　　I ve known him since then. 我从那时起就认识他了。

　　2) 用于 till / until 从句的差异

　　延续动词用于肯定句，表示 做 直到 瞬间动词用于否定句，表示 到 ，才

　　He didn t come back until ten o clock.

　　他到 10 点才回来。

　　He slept until ten o clock.

　　他一直睡到 10 点。

　　典型例题

　　1. You don t need to describe her. I ___ her several times.

　　A. had met B. have met C. met D. meet

　　答案 B. 首先本题后句强调对现在的影响，我知道她的模样，你不用描述。再次，

　　several times 告知为反复发生的动作，因此用现在完成时。

　　2.---I m sorry to keep you waiting.

　　---Oh, not at all. I ___ here only a few minutes.