Be 动词的用法：
(1) Am--was Is --was Are--were 口诀：我用am, 你用are, is用在他她它，复数全用are。
(2) 肯定和否定句 I am (not) from London. He is(not) a teacher. She is(not) in the dining room. My hair is(not) long. Her eyes are(not) small.
(3) 一般疑问句 Am I a Chinese? Yes, you are. No, you aren’t. Are they American? Yes, they are. No, they aren’t. Is the cat fat? Yes, it is. No, it isn’t.
there be 结构
肯定句： There is a …
There are …
一般疑问句:Is there …? Yes, there is./ No, there isn’t.
Are there…? Yes, there are. /No, there aren’t.
否定句： There isn’t …. There aren’t….