— 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
网友回答
A. mustn't
B. won't
(答案→)C. can't
D. needn't
解析：考查情态动词表示推测：句意：--今天杰克值日吗？--不可能是他。明天该轮到他。Can’t be用于否定推测“不可能是”，must表示推测的时候，表示“肯定是”，won’t不愿意，needn’t不必，选C。