could have done是什么時態

　　例句：

　　Her hair could have done with a wash.

　　她的頭發該洗一洗了。

　　I could have done without being woken up at three in the morning.

　　其實用不著在凌晨三點鐘就把我叫醒。

　　She was away from school for 15 weeks, a handicap she could have done without

　　她有15周沒上學，這給她帶來了本不該有的障礙。

　　Whoever could have done such a dreadful thing?

　　究竟是誰能干出這種可怕的事呢？

　　It was hard to visualize how it could have been done.

　　很難想象這是如何辦到的。