—Is Jack on duty today?—It be him. It’s his turn tomorrow. A. mustn’tB. won’tC. can’tD. n

问题补充：

—Is Jack on duty today?

—It be him. It’s his turn tomorrow.

A. mustn’t

B. won’t

C. can’t

D. needn’t

答案：

A. mustn’t

B. won’t

(答案→)C. can’t

D. needn’t

解析：根据下文的It’s his turn tomorrow可知，Jack今天“不可能”(can’t)当班，故应选C。