haven't和have not和don't have这三个有什么区别？分别如何使用？

have not 和haven't没有区别，都是现在完成事态的否定用法。haven‘t是缩写
e.g.:I have finished my homework
变否定：i have not finished my homework
变疑问：have you finished your homework?

don't have是一般现在时的否定形式。要求主语为第一人称，have此处做“拥有”翻译
e.g.: I have a cat
变否定：i don't have a cat
变疑问：do you have a cat?