问题
选择题
—Where are Lucy and Lily?
—Oh , the two girls must _______ a game in the garden now.
A．play
B．are playing
C．played
D．be playing
答案
答案：D
题目分析：此题重点考查情态动词的用法，must为情态动词，后跟动词原形故排除B、C；根据语境：“---露西和莉莉在哪儿？”由now可知表示动作正在进行,故选D
点评：情态动词must表示肯定的猜测，“一定”后跟动词原形；must be doing表示肯定某人正在做某事；例如He must be doing his homework.他一定在做他的作业