—Whoissinginginthenextroom?  —It

问题详情：

—Who is singing in the next room?

   — It _______ be Lucy. She likes singing at this time.

   A. can                     B. must                         C. mustn’t                  D. should

【回答】

B  must be“一定是”，表示推测。

知识点：情态动词

题型：选择题