题目

Jenny _______ have kept her word. I wonder why she changed her mind.A.must B.should C.need D.would 答案：【答案】B【解析】考查情态动词+have done。句意：詹妮本应该信守诺言的。我想知道她为什么改变主意。根据后半句I wonder why she changed her mind.可知，詹妮没有信守诺言，should have done sth.“本应该做某事却没做”符合句意。must have done过去一定做了；needn’t have done本没必要做某事却做了；would have done多用1．3小时20分=3$\frac{1}{3}$小时5.02吨=5吨20千克．