大学英语六级语法基础：
一般现在时，过去时，过去完成时，现在完成时1.一般现在时
（1）表示经常性、习惯性的动作；
eg：I get up at 7 o' clock in the morning.
I leave school for home at 6 every evening.
（2）客观真理，客观存在，科学事实；
eg：The teacher told us: the earth moves around the sun. Shanghai lies in the east of China.
2.一般过去时
两种变化形式：在动词后加ed或不规则变化的动词；
在确定的过去时间里所发生的动作或存在的状态：
常用时间状语有：yesterday, last week, an hour ago, the other day, in 1982等；
eg：Did you go to Shanghai last week?
补充：used to/be used to
（1）used to + do："过去常常"，表示过去习惯性的动作或状态，但如今已不存在；
eg：Mike used to take a walk.
（2）be used to + doing：对……已感到习惯，或"习惯于"，to是介词，后需加名词或动名词；
eg：Mike is used to taking a walk.
He is used to taking a shower with cold water.
（3）be used to do：被用来做……
eg：Leaves are used to fight enemies in Kong fu movies as the weapons.
典型例题
---- Your phone number again? I ___ quite catch it.
---- It's 69568442.
A. didn't
B. couldn't
C. don't
D. can't
答案A. 本句虽没有明确的时间状语，但从语意上看出，在听的时候没有听懂这
个动作发生在过去，因此应用过去时。
2.一般过去式和过去完成时的对比：
（1）过去完成时：
过去的过去；
eg：Before I came to Beijing, I had stayed in Shanghai.
① 一个句子里有两个谓语动词，一个发生在前，一个发生在后，发生在前的用
一般过去时，发生在后的用过去完成时；
eg：When the police arrived, the thieves had run away.
② 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…，却未能…"
eg：We had hoped that you would come, but you didn't. We had
thought that he would take part in the competition，but he didn't.
③ 虚拟语气：
若虚拟的现象与过去事实相反，则用过去完成时；
eg：If you had come to my birthday party, you would have seen Yaoming. 虚拟语气中可以用had+过去分词，表示对过去事实的虚拟；
3. 一般将来时
（1）shall/will, shall用于第一人称，常被will 所代替;
eg：Which paragraph shall I read first？
（2）be going to +不定式，表示将来；表示要发生的事情有了预先的计划、准
备或有迹象表明要发生；
eg：What are you going to do tomorrow?
What will you do this afternoon?
will表示纯粹的将来；
（3）be +不定式：表将来，按计划或正式安排将发生的事；
eg：We are to/will discuss the report next Saturday.
（4）be about to +不定式：意为马上做某事，后面不可以接时间状语；
eg：He is about to leave for Beijing.
注意：
（1）一般现在时有时也可表将来；
eg：The train leaves at six tomorrow morning.
① 趋向性动词come, go, arrive, leave, start, begin, return的一般现在时表将来，主要用来表示在时间上已确定或安排好的事情。
eg：When does the bus star? It stars in ten minutes.
② 在时间或条件句中，用一般现在时表将来；
eg：I'll write to you as soon as I arrive in Beijing.
（2）现在进行时也可表将来：通常用于口语，翻译为打算……；
come, go, start, arrive, leave, stay等词可以用进行时表将来；
3.现在完成时
现在完成时用来表示之前已发生或完成的动作或状态，其结果对现在造成影响。
（1）过去发生的动作发生到现在，刚刚完成；
（2）从过去发生的动作，发生到现在，刚刚告一段落，但是后面会继续发生；eg：I have just finished my homework.
It has rained for 3 days.
过去时与现在完成时的区别：
（1）过去时表示过去某时发生的动作或单纯叙述过去的事情，强调动作；现在
完成时为过去发生的，强调过去的事情对现在的影响，强调的是影响。
eg：I came to Beijing in 1995.
I have stayed in Beijing since 1995.
（2）过去时常与具体的时间状语连用，而现在完成时通常与段的时间状语连用，或无时间状语；一般过去时常用时间状语：yesterday, last week，…ago, in1980, in October…（具体时间）
现在完成时常用时间状语：for, since, so far…（长期的段时间）
eg：He had dinner with me yesterday.
I have played basketball for 3 hours.
（3）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；
eg：He got married two years ago.
I have lived in Beijing for 10 years.
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
---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。