8. 关键字法很多题目都有如此一些词，它们对于迅速而准确的断定答案起着至关要紧有哪些用途，大家称这类词为关键字，找到句中的关键字也就找到知道题的突破口。例8：I saw Kevin in the supermarket this morning.No, it _____ him. He moved to Canada last week.A. can beB. must beC. cant beD. mustnt be由本题的重点He moved to Canada last week.可知在超市见到的那个人肯定不是凯文，故答案为C项。
