Exercise is good us.A. atB. inC. ofD. for

问题补充：

Exercise is good us.

A. at

B. in

C. of

D. for

答案：

A. at

B. in

C. of

(答案→)D. for

解析：be good at擅长……;在某方面做得好.be good in+doing sth. be good for对……有好处。本句意为：锻炼对我们有好处。