am not,aren't,isn't,can't,don't,doesn't.的区别及用法：am not,aren't,isn't 均为系动词否定,后接动词的ing形式、被动形式,am是第一人称is第三人称单数are为复数can't为不能,是情态动词否定don't,doesn't为助动词否定can't,don't,doesn't后接动词原型.
