二、单项填空（共15小题；每小题1分，满分15分）
16. —Would you permit me __________ here?
—Sorry, we don’t permit ＿＿＿＿＿＿here in the lab.
A. smoking; smoking B. to smoke; to smoke
C. smoking; to smoke D. to smoke; smoking
17.Though Tom was impolite to the new teacher，she________him his rudeness.
A．excused B．apologized C．forgave D．punished
18.The letter he had been looking forward to________at last this morning.
A．come B．comes C．coming D．came
19. —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
