—Whoissinginginthenextroom?  —It

問題詳情：

 —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”，表示推測。

知識點：情態動詞

題型：選擇題