should have been done是什么时态

　　I was clear that it should not have been done.

　　我确信那件事是不应该做的。

　　It also adds stress when you know that you have something to do that should have already been done.

　　而且只会让你感觉到有时期应该完成而没有完成的压力。

　　Some argue that such work should never have been done in the first place and call for international monitoring of potentially harmful research.

　　一些人认为根本就不应该做这种工作，并呼吁对潜在的有害研究进行国际监管。

　　It should have been done properly, not messed up like that.

　　活儿该干得有条有理，不是这样乱七八糟的。