As we know, too much ________ to Xrays can cause skin burns, cancer or other damage to the body.
| A．contact | B．appeal |
| C．exposure | D．contribution |
The pressure _____ causes Americans to be energetic, but it also puts them undera constant emotional strain (过度紧张).
| A．to compete | B．competing |
| C．to be competed | D．having competed |
_____ it or not, his discovery has created a stir in scientific circles.
| A．Believe | B．To believe | C．Believing | D．Believed |
After the Arab states won independence, great emphasis was laid on expanding education, with girls as well as boys _____ to go to school.
| A．to be encouraged | B．been encouraged |
| C．encouraged | D．be encouraged |
There's a man at the reception desk who seems very angry and I think he means_____trouble.
| A．making | B．to make | C．to have made | D．having made |
That was so serious a matter that I had no choice but _____ the police.
| A．called in | B．calling in | C．call in | D．to call in |