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。
IV 现在完成时
一、现在完成时的构成式是have(has)＋动词的ED分词
1) Research ［A］ in molecular(分子的) biology has demonstrate ［B］ phenomenal similarities ［C］ between ［D］ humans and apes(类人猿).
2) Gore Vidal has steadily pursue ［A］ a literary career ［B］ remarkable ［C］ for its productivity， versatility(多样性) and unpredictability ［D］ (多变性).
3) For centuries large communities of people have living ［A］ on houseboats in parts ［B］ of the world where ［C］ the climate is warm and the waters are calm ［D］ .
二、现在完成时表示到现在为止的一段时间内发生的情况或动作，强调的是对现在的影响，可能是已完成的动作，也可表示多次动作的总和，或习惯性的行为和持续的动作
4) Ninetyeight percent of all animal species ［A］ in ［B］ history had ［C］ died out ［D］ .
5) The domestic ［A］ dog， considered to be the first tamed animal， is coexisting ［B］ with human beings since ［C］ the days of the cave dwellers ［D］ (居住者).
三、如果句中有表示到现在为止这段时间的状语时，用现在完成时，这些时间状语有 now, today, this week, this month, this year，现在完成时不和表示具体的时间状语连用，如yesterday, last year等，但可以和always, before, just, in／during the past(few weeks, years, fifty years)连用，这时in表示“过去多少时间”，不能用after
6) Industrial ［A］ management is the aspect ［B］ of business ［C］ management that was ［D］ most prominent in the United States in the past eight years.
7) Learning a foreign language is especially ［A］ difficult for those ［B］ who had ［C］ never learned one before ［D］ .
四、在有already, as yet, yet, ever, just, never 这类副词作状语的情况下，用现在完成时
8) In just ［A］ the last ［B］ few years， football is become ［C］ more popular thanbaseball in that country ［D］ .
9) Coupled with the growing quantity of information is the development of technologies which enable the storage and delivery of more information with greater speed to more locations than has been possible before.
［A］ ever ［B］ everest
［C］ more ［D］ most
10) President Andrew Jackson was a controversial ［A］ figure in his own ［B］ day and is one ［C］ ever since ［D］ .
五、有“since＋时间点，for＋一段时间”引导的状语时，主句谓语用现在完成时态
11) Jekyll Island has been one ［A］ of Georgia’s state ［B］ parks ［C］ in ［D］ 1954.