虚拟语气的主句,什么时候用would do?什么时候用would have done?

虚拟语气的主句,什么时候用would do?什么时候用would have done? 虚拟语气中,什么时候用would have done,would do 虚拟语气中对过去的虚拟主句否定是用would have not done or would not have done? 虚拟语气中的would have done 与could have done结构 有什么 区别?什么时候用would什么 虚拟语气would have done 的用法 什么时候用would have done结构 虚拟语气里有would 和could,什么时候用would ,什么时候用could 虚拟语气中had done与would have done,did与would do 的用法有何区别 在虚拟语气中,什么时候用would＋动词原形,什么时候用should＋动词原形 虚拟语气中的would/conld/should do/have done 与 did/had done有何区别 would have done 和would had done 分别用在什么句子中?请举例句说明（虚拟语气的用法） would/could/must have done在虚拟语气中怎么用?