问题
选择题
Mr. Green has two sons, one of _____ working as a bus driver now.
A．who
B．whom
C．them
D．whose
答案
答案：C
考查独立主格结构。根据one of _____ working as a bus driver now中没有谓语动词可知不是从句，them指代前文提到的两个儿子，选项ABD一般用于引导定语从句，故选C。格林先生有两个儿子，他们其中一个现在做公交司机。