Jack almost fell off the cliff, but managed to _____ until help came.
| A．keep on | B．catch on | C．count on | D．hang on |
The old man stood there with his eyes ______ on the picture.
| A．to focus | B．focusing | C．focused | D．focus |
Scientists are convinced ______ the positive effect of laughter ______ physical and mental health.
| A．of; at | B．by; in | C．of; on | D．on; at |
---I’m going out tonight.
---Well, I’d rather you ______.
| A．not | B．aren’t | C．didn’t | D．won’t |
Bitten twice, the postman refused to ______ our letters unless we changed our dog.
| A．deserve | B．deliver | C．expand | D．direct |
______ to go abroad alone is what worries me most.
| A．The boy not allowing |
| B．The boy not being allowed |
| C．The boy’s being not allowed |
| D．The boy’s not being allowed |