isn't doesn't don't的区别

Question

最好有例子啊。
那isn't和doesn't有什么区别啊？

Answer 1

isn't 主语为第三人称单数，时态为一般现在时，后不加动词，加名词，形容词等．doesn't主语也为第三人称单数，时态也为一般现在时，但后加动词原型．
don't 主语为第一二人称或复数，时态也为一般现在时，后也加动词原型．

Answer 2

don't doesn't 是助动词do的否定形式，意为不能做什么。
例：I _don't_ know what you say.（我听不懂你在说什么。）
doesn't是第三人称单数。例：He dosen't see.（他不能看。）

而isn't 是be动词is的否定形式。It isn't necessery.（这不重要。）

Answer 3

isn't是现在进行体 表“是，有” 用于第三人称单数
She isn't a doctor
She isn't playing basketball
There isn't any sheep

doesn't是一般现在时 用于第三人称单数
He doesn't good at dance

don't是一般现在时 用于第一人称和第二人称 以及复数情况
I don't kown
You don't understand me
They don't like him