be supposed to do与was/were supposed to have done

be supposed to do 是指应该去做什么
was/were supposed to have done 是指一种虚拟，是指本来应该做的，但是事实上并没有发生
例如you were supposed to have finished the work,but i haven't seen it now

be supposed to do 被期望做某事
was/were supposed to have done 被期望做完某事，却没有做。