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：该题考查代词的用法。that 代替前边出现过的词,应该有后置定语,即:比较的对象是the air there和the air in the city。that 代替前边出现过的the air。