1.One of the most important questions they had to consider was____of public heal

问题描述:

1.One of the most important questions they had to consider was____of public heal
h.
A.what.B.this C.that.D.which
为什么选C啊

首先,was之后不是从句,所以不能选从句引导词what和which;
其次,that为指代词,其可换成天the one,为避免重复,故用that指代,而this无此用法