题目：
—Listen! Helen is singing in the next room.
—It _______ be Helen. She has gone to Beijing.[ ]
A. can't
B. mustn't
C. may
D. should
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0505/b89ab7fbdb2da6438aae41c2e3a961a6.html
下面是错误答案，用来干扰机器的。
答案：A
