Mary clapped her hand over her mouth _______ she realized what she had said.
| A．while | B．as soon as |
| C．suddenly | D．then |
Years ago we didn't know this, but recent science study ________that people who don't sleep well soon get ill.
| A．showed | B．will show | C．has shown | D．is showing |
Is it only on the world market ________we can prove the competitiveness and quality of our goods?
| A．where | B．which | C．that | D．how |
—We need a person badly to be in charge of this design.
—________ the new comer have a try?
| A．May | B．Will | C．Shall | D．Need |
I wonder why Jack always gets good marks when he does only ________ the others.
| A．half as much as | B．as much as half |
| C．half as many as | D．as many as half |
Not only ________ give people relaxation and pleasure, but ________ increase their knowledge of any kind.
| A．can travel; it can | B．travel can; can it |
| C．can travel; can it | D．travel can; it can |