there与have的区别

have 人为有（即某人有某物或某物有……
there is 存在有（ 即某地有某物,主语是单数）
there are 存在有（即；某地有某物,主语是复数）
如
I have two books 。
A dog has four legs 。
There is a book in my bag 。
There are two books in my bag 。
希望能解决您的问题。