Although medical science________control over several dangerous diseases，what worries us is that some of them are recurrent.
| A．achieved | B．has achieved |
| C．will achieve | D．had achieved |
________ you are supposed to do ________ you don't like a thing is change it. Don't complain.
| A．That; why | B．What; when |
| C．What; where | D．That; how |
His younger sister may already be in high school now, in ________ case this picture book is too childish for her.
| A．that | B．which |
| C．whose | D．what |
It is by no means clear ________ the president can do something to end the strike.
| A．whether | B．which |
| C．that | D．what |
Good shoes, clothes and a backpack are the basic ________ you need for your hiking.
| A．equipment | B．instruments |
| C．tools | D．models |
The Australian boy has a good ________ of Chinese and can express himself freely in it.
| A．power | B．command |
| C．demand | D．usage |