Question

有must/could/can/may/maight have been done吗

Answer 1

1. can,could 比 may,might的可能性大些。
can, could 之间的区别，和 may,might 之间的区别在于，虚拟句和过去时态用后者，表示的可能性比原词小，但大部分时候2者可以互换，不会产生歧义或者对表述造成干扰。
2. could have done, might have done 是过去完成时态，不知你问的“可能性”是何意。
例如，Do not point me with a gun ever! I could have been killed. 意思是"以后别在用枪指着我了，会出人命的！" 意思是point me with a gun 这件事情已经发生过了，所以才说那时候会差点没命。
但是如果说 Do not point me with a gun, I can be killed. 是警告，point me with a gun这件事还没有发生，只是说可能会出人命而已。
3. 过去时态用 could, might. 例子：If it wasn't you, I could have finished my job by now. 如果不是因为你，我现在应该已经完成工作了！
could 表示有这个能力；而这个句子之所以不用might have finished my job,是因为might表示的可能性太小，没有足够的说服力去职责别人。

追问

他工作起来一定很认真 ［表推测］怎么用

Answer 2

都有

Answer 3

may have done and could have done 区别

Answer 4

哈哈