Robert saw two boys making fun ________ an old man, and then he stopped them.
| A．in | B．on |
| C．at | D．of |
She does her homework as____as I.
| A．care | B．careful | C．carefully | D．careless |
I’m sorry for____all your books on the desk.
| A．knock over | B．knock off |
| C．knocking about | D．knocking down |
We were swimming in the lake _______ suddenly the storm started.
| A．until | B．while | C．when | D．before |
The price of petrol(汽油) is not _______ that of last year, so some more people are planning to buy cars.
| A．as expensive as | B．so cheap as |
| C．as low as | D．so high as |
Everybody should study hard. No one can _______ us _______ a good future.
| A．provide; for | B．provide; with |
| C．keep; / | D．protect; to have |