问题
单项选择题
The agency, ______ to set and enforce health standard for American workers, has been promising a cotton dust standard for several years.
A．which is
B．which it is
C．whose job it is
D．of whose job is
答案
参考答案：C
解析：应选非限定性定语从句whose job it is…，相当于it is the agency's job to set and enforce…