英语一般现在时(Simple present tense)。表示通常性、规律性、习惯性、真理性的状态或者动作(有时间规律发生的事件)的一种时间状态。
动词的现在式有am，is，are三种，分别接在不同人称的主语之后：
1.be动词是系动词的一种，表示“……是……”的意思。
现在式（The Present Forms）有am，is，are三种。这三种动词的原形是be，所以它们称为be动词。
2.be动词的现在式
be动词的现在式有am，is，are三种，分别接在不同人称的主语之后：
be动词句型的构成
肯定句：主语 be动词（am/is/are）...
否定句：主语 be动词（am/is/are） not...
疑问句：be动词（am/is/are） 主语...?
疑问代词/疑问副词 be动词（am/is/are） 主语...?
3. be动词的肯定句
句型：主语 be动词...
be动词的肯定句由“主语 be动词（am/is/are） 表语”构成：
I am a doctor.
我是一名医生。
Mary is at work.
玛丽在工作。
He is very brilliant.
他非常聪明。
It is a nice day.
今天天气晴朗。
You are my only friend.
你是我惟一的朋友。
They are students.
他们是学生
。4 be动词的否定句
句型：主语 be动词（am/is/are） not...
be动词一般现在时的否定句结构，是在be动词am，is，are之后加not：
We aren't her classmates.
我们不是她的同班同学。
I'm not Tom.
我不是汤姆。（I'm是I am的缩写，读作/aim/。）
It's not a cat，but a dog.
这不是猫，而是狗。
Things are not always what they seem（to be）.
事物并不总是与表象一致。
be动词否定句的缩写方式：
is not的缩写是isn't，读作/′iznt/；are not的缩写是aren't，读作/a：nt/；I am～的否定句是I am not～，缩写为I'm not～；am not不缩写在一起。
be动词的一般疑问句
句型：be动词 主语...?
回答方式：Yes，主语 be动词（am/is/are）...
No，主语 be动词（am/is/are） not...
1.I ______ cooked a meal when you _____ me.
A. cooked, were ringing B. was cooking, rang
C. was cooking, were ringing D. cooked, rang
2.He said he _____ to draw a plane on the blackboard at that time.
A. tries B. tried C. was trying D. will try
3.While she ______ TV, she ______ a sound outside the room.
A. was watching, was hearing B. watched, was hearing
C. watched, heard D. was watching, heard
4.They _____ a football game from 7 to 9 last night.
A. were watching B. watch C. watched D. are watching
5.What book ____ you ______ when I ____ you at four yesterday afternoon?
A. did, read, was seeing B. did, read, saw
C. were, reading, saw D. were, reading, was seeing