should have done和shouldn't have done，couldn't have done是什么意思

should have done:本应该做了某事
shouldn't have done:本不应做某事
could't have done ：（表推测）不可能做了某事

should have done:本应该做某事却没做
shouldn't have done:本不应做某事却做啦
could't have done ：（表推测）不可能做了某事
以上都是虚拟语气

应该完成
不应该完成
不能完成

所有的done也可以换成是做的意思。