概要：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.(我现在已不在这里工作。)I have worked here for many years.(现在我仍在这里工作。)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。1) (对) Tom has studied Russian for three years.= Tom began to study Russian three years ago, and is still studying it now.2) (错) 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.
小升初英语语法复习－动词时态2,标签：小学英语语法大全,http://www.85jc.com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.
(我现在已不在这里工作。)
I have worked here for many years.
(现在我仍在这里工作。)
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。
1) (对) Tom has studied Russian for three years.
= Tom began to study Russian three years ago, and is still studying it now.
2) (错) 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.
11.13 since的四种用法
1) since +过去一个时间点 (如具体的年、月、日期、钟点、1980, last month, half past six)。
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.
11.14 延续动词与瞬间动词
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。 (表结果)
I've known him since then. 我从那时起就认识他了。(表经历)
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.
A. have been B. had been C. was D. will be
答案A. 等待的动作由过去开始，持续到现在，应用现在完成时。
11.15 过去完成时
1） 概念：表示过去的过去
----|-------|-----|---->其构成是had +过去分词构成。
那时以前 那时 现在
2） 用法
a. 在told, said, knew, heard, thought等动词后的宾语从句。
She said (that) she had never been to Paris.
b. 状语从句
在过去不同时间发生的两个动作中，发生在先，用过去完成时；发生在后，用一般过去时。
When the police arrived, the thieves had run away.
c. 表示意向的动词，如hope, wish, expect, think, intend, mean, suppose等，用过去完成时表示"原本…，未能…"
We had hoped that you would come, but you didn't.
3) 过去完成时的时间状语before, by, until , when, after, once, as soon as。
He said that he had learned some English before.
By the time he was twelve, Edison had began to make a living by himself.
Tom was disappointed that most of the guests had left when he arrived at the party.
典型例题
The students ___ busily when Miss Brown went to get a book she ___ in the office.
A. had written, left B，were writing, has left C. had written, had left D. were writing, had left
答案D. "把书忘在办公室"发生在"去取书"这一过去的动作之前，因此"忘了书"这一动作发生在过去的过去，用过去完成时。句中when表示的是时间的一点，表示在"同学们正忙于……"这一背景下，when所引导的动作发生。因此
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