Guess what!I have got A for my term paper!

题目

Guess what!I have got A for my term paper!
Great!You _____ read widely and put a lot of work into it.
A.must B.should C.must have D.should have
我知道应该是选A或者C,must have是对过去情况的肯定推测
"got A"算不算过去的事?应该算过去吧..因为已经得了A,可也算现在时啊,因为两人正在对话

答案

C must have done 对过去发生事情的一种推测,过去坑定做过某事.