Infinite Tense(一般现在时)
1.现在一般时(Present Indefinite Tense)的用法：动词be第一人称单数用am，第三人称单数用is外，其余一律用are；动词have除第三人称单数用has外，其余一律用have；行为动词的现在一般式，除第三人称单数由动词原形加词尾–s或–es构成外，其余一概和动词原形同形。
1) 表示习惯、经常发生的动作或存在的状态。常与下列时间状语连用every day, often, usually,always, seldom, sometimes, twice a week等。
Professor Liu is our English teacher.
The children go to school at seven every morning.
2)表示主语的特征、性格、能力等。
Do you like sports?
Picasso draws well.
3)表示客观事实或普遍真理。
The sun rises in the east.
It’s hot in summer.
4)现在一般时的特殊用法
a.在时间、条件状语从句中，主句用一般将来时，从句用一般现在时表将来。
If you see her, will you tell her to ring me up?
When the class is over, the student will go to the library.
b.祈使句都用动词原形，其反义疑问句用。
See a film tonight, won’t you?
c.引用报刊书籍时，一般用现在时。
The story describes how a young scientist develops a new theory.
d.主句中的谓语动词如是过去时，其宾语从句的谓语动词一般也须用过去时态，但宾语从句说的是客观事实时，它的谓语动词仍用现在一般时。
Galileo insisted that the earth moves round the sun.
2.过去一般时 (Past Indefinite Tense) 的用法：由规则或不规则动词的过去式表示，除be动词外其它动词的过去式没有人称和数的变化。
1)表示过去某一时间的动作或状态，常伴有具体的时间状语。如：yesterday, two days ago, last week, in 1920等。
I forgot to close the window yesterday.
When he was in the countryside, he often swam in the river.
2)叙述发生在过去的一件事。
The doctor got up, dressed and drove to the hospital within five minutes.
3)在时间、条件状语从句中，主句用一般过去时，从句也用一般过去时表示过去将来。
They said they would let us know if they heard any news abouthim.
He promised me that he would buy me a book when he got to the bookstore.
3.将来一般（Future Indefinite Tense）时的用法：由shall(第一人称)或will(第二、三人称)+动词原形构成。
1) 表示将来的动作或状态
I shall come to see you the day after tomorrow.
The indoor swimming pool will be open to the public from October 1.
2)其它表示将来的说法
a.“主语 + be going + 动词不定式”，多用于口语，表示要去做的事。
We are going to visit the Museum of Chinese History.
What are you going to do today?
b.“主语 + be about to + 动词不定式”，表示即将发生的事。
We are about to leave, so there is no time to visit Mr. Wang.
c.“主语 + be + 动词不定式”，表示安排或计划好了的事。
The Minister is to give us a speech next Friday.
d. go, come, have, start等表示动作的动词，可用现在进行时表示即将发生的动作。
He is not coming.
4.过去将来一般时(Future-in-the-past Indefinite Tense)的用法：由should(第一人称)和would(第二、三人称)加动词原形构成。
1) 过去将来一般时常用于宾语从句中
They wanted to know when you would hand in your homework.
I phoned him that I should leave for Shanghai next Tuesday.