16. —Who it be that is knocking at the door? —It be Father but I’m not sure. A. can; mus

问题补充：

16. —Who it be that is knocking at the door?

—It be Father, but I’m not sure.

A. can; must

B. can; may

C. must; can

D. may; must

答案：

A. can; must

(答案→)B. can; may

C. must; can

D. may; must

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