_____ to nuclear radiation, even for a short time, may produce variants (变异体) of genes in human bodies.
| A．Exposed | B．Being exposed |
| C．Having exposed | D．After being exposed |
I remember a ____ famous scientist said that we should believe in ourselves first of all.
| A．some | B．certain | C．sure | D．other |
Have you got any particular plans for the coming holiday?
Yes. _____, I’m going to visit some homes for the old in the city.
| A．If ever | B．If busy | C．if anything | D．if possible |
_____ get a better score, she has been studying hard all day.
| A．So as to | B．In order to | C．So that | D．In order that |
It was necessary to _____ the factory building as the company was doing more and more business.
| A．extend | B．increase | C．lengthen | D．magnify |
The two parties are holding the talk in a friendly________ at present. Hopefully，they will reach an agreement.
| A．atmosphere | B．condition |
| C．situation | D．phenomenon |