公共英语二级考试语法精选讲解
引导语：下面是小编整理的一些公共英语二级考试的语法精选讲解，语法盲的同学可要认真看看啦，小编觉得学习语法要掌握规律，循序渐进，这样才能更好地把握语法要领。
比较过去时与现在完成时
现在完成时可表示持续到现在的动作或状态，动词一般是延续性的，如live, teach, learn, work, study, know.
过去时常用的非持续性动词有come, go, leave, start, die, finish, become, get married等。
举例：
I saw this film yesterday.
(强调看的动作发生过了。)
I have seen this film.
(强调对现在的'影响，电影的内容已经知道了。)
Why did you get up so early?
(强调起床的动作已发生过了。)
Who hasn't handed in his paper?
(强调有卷子，可能为不公平竞争。)
She has returned from Paris.
她已从巴黎回来了。
She returned yesterday.
她是昨天回来了。
He has been in the League for three years.
(在团内的状态可延续)
He has been a League member for three years.
(是团员的状态可持续)
He joined the League three years ago.
( 三年前入团，joined为短暂行为。)
I have finished my homework now.
——Will somebody go and get Dr. White?
——He's already been sent for.
句子中如有过去时的时间副词(如 yesterday, last, week, in 1960)时，不能使用现在完成时，要用过去时。
(错)Tom has written a letter to his parents last night.
(对)Tom wrote a letter to his parents last night.
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。
It is the first time that I have visited the city.
It was the third time that the boy had been late.
2)This is the… that…结构，that 从句要用现在完成时.
This is the best film that I've (ever) seen.
这是我看过的最好的电影。
This is the first time (that) I've heard him sing.
这是我第一次听他唱歌。
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。This is the 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。
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.
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