一般现在时表示现在、经常或习惯的动作或状态和普遍现象、常识或客观真理；一般过去时用于过去某一时间内发生的或过去习惯性的动作或状态；一般将来时表示将要发生的动作或存在的状态，将来打算做的事情；现在完成时表示过去发生的动作造成目前的结果和对现在造成的影响或表示从过去延续至今的动作、状态和习惯等；将来完成时表示将来某时之前业已完成或发生的事情；过去完成时表示过去某时间之前已经发生的动作或状况，即过去的过去。注意每一种时态与其他时态的交叉使用情况。英语共有十六种时态，其表现形式如下(以study为例)：
| 一般时 | 进行时 | 完成时 | 完成进行时 | |
|---|---|---|---|---|
| 现在 | study studies |
am studying is studying are studying |
have studied has studied |
have been studying has been studying |
| 过去 | studied | was studying were studying |
had studied | had been studying |
| 将来 | shall study will study |
shall be studying will be studying |
shall have studied will have studied |
shall have been studying will have been studying |
| 过去将来 | should study would study |
should be studying would be studying |
should have studied would have studied |
should have been studying would have been studying |
考试中出现的一般有以下几种。
VI 进行时态
一、现在进行时表示现在或现阶段进行的动作，但也和always, constantly, forever等频度副词连用表示一个经常进行的动作或现在存在的状态
1) Because of ［A］ the effects of tidal friction(摩擦力)， the earth’s rotation， which forms ［B］ the basis for time units， is ［C］ gradually slow down ［D］ .
2) All things ［A］ consist of ［B］ atoms or molecules，which be ［C］ constantly moving ［D］ .
二、瞬间动词和一些表示状态及感觉的动词一般不用进行时，而用一般现在时或一般过去时代替。这些动词包括：appear(显然), arrive, be, come, desire, go, find, hate, hope, join, know, leave, like, love, join, possess, start, sail, see, suggest, taste, think(认为), understand等，类似的动词还有belong to， consist of，seem(似乎)等
3) He was seeing ［A］ somebody creeping ［B］ into the house through ［C］ the open ［D］ window last night.
4) Among ［A］ the most important ［B］ jazz innovators ［C］ in the twentieth century are being ［D］ Louis Armstrong， Fletcher Henderson， Duke Ellington， and Dizzy Gillespie.
三、过去完成进行时
过去完成进行时表示到过去的某一时间点或某一时间段里一直在进行的动作或行为
5) They received the parcel that they for a long time.
［A］ expected ［B］ have expected
［C］ had been expecting ［D］ had expected
There is a wellknown incident in one of Moliere′s plays, where the author makes the hero express unbounded delight on being told that he had been talking prose during the whole of his life.(93年翻译)
四、例题解析
1) D错。slow只有作为不及物动词用时才与up或down连用，表示“慢慢向上”或“慢慢向下”。所以我们说，这里的slow是动词而不是形容词，应将动词slow后边加上“ing”，改为(is) slowing down，构成现在进行时。
2) C错，改为are。
3) A错，改为saw。
4) D错，改为are。
5) C为正确答案。