题目

There are several theories about why dinosaurs suddenly died out, one of which says their disappearance _______ by the climate change.A. might have caused B. should have causedC. might have been caused D. should have been caused 答案：【答案】C【解析】考查情态动词加完成式。句意：关于恐龙为何突然灭绝有几种理论，其中一种认为恐龙的消失可能是气候变化造成的。might have done表示对过去事情没有把握的肯定推测，“可能已经做了某事”，且句子主语disappearance和cause之间是一种被动关系，所以用被动式，故答案为C。98的后面两个数是、。