30. More than 20 years ago he was badly wounded in the anti-Vietnam war. Since then he can only walk _____ an arm-chair .
| A．in | B．on | C．by | D．Over |
—Can I come to ask for some advice at any time?
— Yes, of course. _______
| A．If you’re convenient. | B．At your convenience. |
| C．Don’t worry. | D．Don’t mention it. |
My father is clearly in____ dilemma about how to handle___ quarrel between us.
| A．the; a | B．/; the | C．a; the | D．a; / |
The headmaster told us ____ football in the teaching building.
| A．to not play | B．not to play | C．not playing | D．not played |
I’m not sure whether this is the book ______ my brother read the year before last.
| A．whose | B．as | C．what | D．which |
When the thief found the police had already ______ him, he ran away quickly.
| A．realized | B．known | C．heard | D． recognized |