否定句到底什么时候用doesn't什么时候用isn't?谢谢!

Question

否定句到底什么时候用doesn't什么时候用isn't?谢谢!

Answer 1

doesn't 和 isn't 是 does 和 is 的否定词（或反义词）,因此 doesn't / isn't 的用法和 does / is
一样, 也就是说,
He/she/it doesn't 表达动作,即 他/她/它 "做" 或 “操作” 某某事,通常接动词
而
He/she/it isn't 表达状态, 即 他/她/它 “是” 某某 东西 或 “处于” 某某状态 ,通常接名词,形容词或动词进行时态（现在分词）
例句：
He doesn't go sailing anymore, ever since his boating accident.
He isn't a carefree person that he used to be, ever since the mishap.
He isn't carefree like he used to be, ever since the mishap.
With the memory of the accident still fresh in mind, he isn't going sailing much.