16. Mary, we left you in _______ charge of the room, but now it’s in _______ mess!
A. the, a B. /, a C. the, / D. /, the
17. You stepped into the lab with your shoes on? You’re ____ to take them off before you enter it. A. invited B. supposed C. forbidden D. permitted
18．His parents insist on_____ to college.
A. him going B. he should go C. him to go D. he go
