英语中的时态一共有八种，它们是：一般现在时、现在进行时、一般过去时、现在完成时、一般将来时、过去进行时、过去完成时、过去将来时。

一般现在时

     一般现在时—表示一般性，经常性的动作或一般性事实。

1、含有be动词的句子
     He is a teacher.
     The girl is very beautiful.
     Tim and Jack are students.

★变疑问句将be动词移到句首
     Is he a teacher?
     Is the girl very beautiful?
     Are Tim and Jack students?

★变否定句在be动词后面加not
     He is not a teacher.
     The girl is not very beautiful.
     Tim and Jack are not students.

★肯定回答及否定回答
     Yes, he is. / No, he is not.
     Yes, she is. / No, she is not.
     Yes, they are. / No, they are not.

2、不含有be动词的句子，即含有一般动词的句子。

(1)第三人称单数及单数名词
     He likes books.
     She likes him.
     The dog likes bones.

★变疑问句在句首加does, 动词变为原型
     Does he like books?
     Does she like him?
     Does the dog like bones?

★变否定句在主语及动词之间加doesn't, 动词变为原型，原句中的动词不再有第三人称变化。
     He doesn't like books.
     She doesn't like him.
     The dog doesn't like bones.

★肯定回答及否定回答：
     Yes, he does. / No, he doesn't.
     Yes, she does. / No, she doesn't
     Yes, it does. / No, it doesn't.

注意：第三人称单数形式一般在动词后面加S，不要和名词复数混淆，变否定句或疑问句时名词复数没有任何变化。

(2)其他人称及复数名词
     I want to have a bath.
     We have some meat.
     The students like smart teachers.

★变疑问句在句首加do
     Do you want to have a bath?
     Do we have any meat?
     Do the students like smart teachers?

★变否定句在主语和动词之间加don't.
     You don't want to have a bath.
     We don't have any meat.
     The students don't like smart teachers.

★肯定回答及否定回答
     Yes, I do. / No, I don't.
     Yes, we do. /  No, we don't
     Yes, they do. / No, they don't.