With an appropriate modal verb: (1)Helen____ go on the trip with

With an appropriate modal verb:
(1)Helen____ go on the trip with us, but she isn't quite sure yet.
(2)____ you play the piano at such a late hour?
【正确答案】：may;Must
【题目解析】：【考点点击】本题考查情态动词。【要点透析】第一个空由后半句“她还没有确定”可知,空处缺少一个表示推测的词,may意为“可能…”,表示不太肯定的推测,符合题意。must表达说话人不满的态度,意思是“偏偏要……;非得…”,符合题意。