单项选择题
A. it helps mice sleep well B. it keeps fatty tissue from growing C. it controls eating D. it prevents overeating
A. The damage was not serious at all. B. He was not careful enough. C. It had been skillfully repaired. D. The salesman only tried it out smoothly.
A. People who have cancer. B. People who like to quarrel with others. C. People whose living standard is low. D. People who have more responsibilities than they can handle.