初中英语语法总结三

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　　11 用于现在完成时的句型
　　1）It is the first / second time.... that…结构中的从句部分，用现在完成时。例如：
　　It is the first time that I have visited the city. 这是我第一次访问这城市。
　　This is the first time （that） I've heard him sing. 这是我第一次听他唱歌。
　　注意：It was the third time that the boy had been late.
　　2）This is +形容词最高级+that…结构，that 从句要用现在完成时。例如：
　　This is the best film that I've （ever） seen. 这是我看过的最好的电影。
　　典型例题
　　（1） ---Do you know our town at all? ---No, this is the first time I ___ here.
　　A. was B. have been C. came D. am coming
　　答案B. This is the first time 后面所加从句应为现在完成时，故选B。
　　（2） ---Have you ____ been to our town before? ---No, it's the first time I ___ here.
　　A. even, come B. even, have come C. ever, come D. ever, have come
　　答案D. ever意为曾经或无论何时，反意词为never，此两词常用于完成时。
　　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。
　　（错）I have received his letter for a month.
　　（对）I haven't received his letter for almost a month.
　　11.12 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。例如：
　　I have lived here for more than twenty years.我住在这儿二十多年了。
　　I have lived here since I was born. 我从出生起就住在这儿了。
　　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。）
　　注意：用句型转换的方法，很容易排除非延续动词在有for/since结构的完成时中的误用。
　　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）。例如：
　　I have been here since 1989. 1989起，我一直在这儿。
　　2） since +一段时间+ ago。例如：
　　I have been here since five months ago. 我在这儿，已经有五个月了。
　　3） since +从句。例如：
　　Great changes have taken place since you left. 你走后，变化可大了。
　　Great changes have taken place since we were here. 我们走后，变化可大了。
　　4） It is +一段时间+ since从句。例如：
　　It is two years since I became a postgraduate student. 我考上研究生有两年了。
　　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。例如：
　　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……"。例如：
　　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。