Have有四种用法：
1,动词,“有”的意思.
I have a book.我有一本书.
Do you have a book?
I don’t have a book.（也可以说I haven’t a book.不常用）
2,助动词.“使……”
have sb do 让某人做
have sb doing 让某人一直做
have sb/sth done 某人/某物被……
3,have to,“不得不,必须”,表示不是主观意愿
It’s dark outside,I have to go home.天黑了,我不得不回家.
Do you have to…….
I don’t have to…….
4,用于完成时
have+动词的过去分词
