You should have watered the tree,_______?

问题描述:

You should have watered the tree,_______?
A.shouldn't you B.didn't you C.don't you D.haven't you
为什么答案是B,请说明原因.急呀,

是该选B
前面是一个虚拟语气
意思是你本应该给树浇水的吧?意思就是你应该这样做你却没有这样做 是过去的动作
所以反问就是didn't you