look!Lucy is playing table tennis with Lily on the playgroud.They____be Lucy and Lily.they have
问题描述：
look!Lucy is playing table tennis with Lily on the playgroud.They____be Lucy and Lily.they have
gone to Hangzhou.
A.mustn't B.must C.can't
答
C can't
look!Lucy is playing table tennis with Lily on the playgroud.They（can't）be Lucy and Lily.they have gone to Hangzhou.
很肯定的否定猜测用 ：can't.
musn't 意思是：禁止.不能选.