Question

Robert saw two boys making fun ________ an old man, and then he stopped them.

A．in	B．on
C．at	D．of

Answer 1

D

试题分析：句意：罗伯特看到两个男孩在开一个老人的玩笑，然后他阻止了他们。make fun of sb开……的玩笑。根据句意，故选D。