The effect a teacher has children may be greater than that of their parents.A. in B. onC.

问题补充：

The effect a teacher has children may be greater than that of their parents.

A. in

B. on

C. at

D. with

答案：

A. in

(答案→)B. on

C. at

D. with

解析：句意：一个老师的影响对孩子可能比他们父母的影响更大。have an effect on 对……的影响。a teacher has children作定语从句修饰先行词the effect.故选B。