—Sorry, sir. I can’t answer this question.
---Well, you are supposed this part of history.
A. reading
B. to be reading
C. to have read
D. having read
网友回答
A. reading
B. to be reading
(答案→)C. to have read
D. having read
解析：考查虚拟语气：be supposed to have done 表示本来应该已做了某事，但可能没做。是一种虚拟语气，句意：--对不起，老师，我不会回答这个问题。--你应该读过历史的这个部分。选C。