Im moving to the countryside because the air there is much fresher than in the city.A.

问题补充：

Im moving to the countryside because the air there is much fresher than in the city.

A. ones

B. one

C. that

D. those

答案：

A. ones

B. one

(答案→)C. that

D. those

解析：考查代词的用法。that代替air。