couldn't have done,"不可能已经"?请举例说明用法?

should have done ,shouldn't have done.could have done,couldn't have done couldn't have done和couldn't do的区别 they couldn't have done better是什么意思 should have done和shouldn't have done,couldn't have 求两组英语句型的解释could have done 和 couldn't have doneshould have done 和 shouldn't have done couldn't have done和mightn't have done有什么区别 couldn't have done,不可能已经?请举例说明用法? 英语中何时使用wouldn,t have done shouldn,t have done couldn,t have done needn,t have donewouldn have done shouldn have done could have done needn have done 呢 couldn't have done与couldn't区别以及当could have done表示对过去的猜测时,could have done与could有什么区别? can have done和could have done有无区别?can't have done和couldn't have done有无区别?如果有,区别是什么? I couldn’t have hoped for a better outcome什么意思,另外can't have done和couldn't have done什么区别 couldn't have done?couldn't have done究竟表示对过去的否定推测,还是表示本不能做到的事做到了? couldn`t have done 不用于虚拟语气 么couldn`t have done 不用于虚拟语气 那要是说 本不能够做..怎么表达 有没有can have done sth?could have done sth有两种意思吗?can't/couldn't have done sth意思又是什么能不能举几个例子? 情态动词＋have donemust have done/can't have doneshould have done/shouldn't have doneneed have done/needn't have donemay(might) have done/haven't donecould have done/couldn't have donewould have done/wouldn't have done如何用?我这样分正 couldn't have done 有 不可能的意思吗?问题二它和cant have done的区别 看很多书上说,couldn't/mightn't have done没有虚拟的意思.那么without your help,we couldn't have finished the work so soon.中的couldn't have done难道不是虚拟吗.请详述~谢谢 He couldn't have done this怎么改被动语态啊