Question

One of the most important questions they had to consider was__________ of public health

A．what	B．this
C．that	D．which

Answer 1

C。

句意为：他们必须考虑其中最重要的问题是公共卫生。考查that作代词，that 作代词，往往用于特指，相当于“that＋名词”，它也只能代替事情不能代替人。