(一)一般现在时
1. 表示自然现象与普遍真理。
The Sun rises in the east.
Actions speak louder than words. 行动胜于语言。
2. 在时间、条件从句中表将来。
I’ll tell him when he comes.
They will do it if they are not very busy tomorrow. 来源：考试大
注意：如果if从句表示一种愿望时，可用will+动词原形，will相当于情态动词。
If you will be quiet, I’ll tell you what happened.
(二)现在进行时
1. 动词go, come, leave, stay, start, do, begin, arrive等动词的进行时表示一个最近计划和安排要做的事。多用于口语。
What are you doing next Saturday?
You may catch the Golden Queen which is sailing to Brazil this afternoon.
你可以乘坐金皇后号，这艘船今天下午将驶往巴西。
2. 进行时与always, constantly, forever等词连用表示感情色彩。
He is continuously finding fault with me. 他不断地挑我的毛病。
These kinds of persons are always doing things like that. 这种人经常那么干。
3. 在由while引起的状语从句中，动词要用进行时。
While you are resting, I’ll read you today’s news.
While I was having my breakfast the morning post came.
(三)现在完成时 来源：考试大
1. 在时间、条件状语从句中，用现在完成时代替将来完成时。
I’ll give this dictionary to you as soon as I have finished reading it.
If you have done the experiment, you will realize how difficult the theory is.
2. 现在完成时可用于下列句型：
This /That /It is the first … that …
This /That /It is the best … that …
This /That /It is the only … that …
This is the first time that I have played table tennis.
It is the only party that I’ve ever really enjoyed in my life.
That is the most interesting film that I’ve ever seen.
3. 无论since作介词还是连词，句子应用完成时。
Great changes have taken place since the reform and opening to the world.
I haven’t seen her since I last saw her.
4. 当since, before作副词用置于句末时，应用完成时。
I haven’t studied English before.
We haven’t met each other since.
5. 在it is … since结构中，主句的谓语通常用一般现在时，也可用现在完成时，但从句通常为终止性动词的过去时。
It’s a long time since I saw you last time.
It is four years since Tom left school.
