-- Look at the boy running on the ground. Is it David?
-- It be him. I saw him go to the teacher’s office just now.
A. might
B. could
C. can’t
D. mustn’t
网友回答
A. might
B. could
(答案→)C. can’t
D. mustn’t
解析：本题的含义是我看见他去了老师的办公室，所以在操场上跑步的男孩不可能是戴维，故本题填不可能的单词can’t，故本题选C。