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
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
B