Many children your age are always a good mood to do the things they’re interested in.A.

问题补充：

Many children your age are always a good mood to do the things they’re interested in.

A. at, in

B. of, in

C. at, on

D. of, with

答案：

A. at, in

(答案→)B. of, in

C. at, on

D. of, with

解析：children of your age 是与你同龄的孩子的意思；in a good mood to do是有…的兴致，想做的意思。都是固定用法。所以本题选B。