—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
网友回答
A. play
B. are playing
C. played
(答案→)D. be playing
解析：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