Mary has got a full mark in the test.She _______very hard all these days
问题描述：
Mary has got a full mark in the test.She _______very hard all these days
A.must have worked B.may work
A和B用哪个好?
答
A.must have worked
肯定是A了!由前文Mary has got a full mark in the test（玛丽考了个满分）,可见下文是对她以前的学习态度进行推测的
对已存在,发生的事实作以肯定推测,要用：
【must(may) + have+ 过去分词】
意为：
她这段时间学习一定很用功
请在客户端右上角评价点“满意”即可,嗯。。。。我也觉得是A。。。但是坑爹的答案说是B。。愁死了答案错误多的是