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

解析:

考查代詞。分析句子結構可看出they had to consider是定語從句，可見was是系動詞，根據選項可判斷后面不是句子，不需要疑問詞，排除A和D。通過句子結構的分析空格應是指上文的question這個名詞。語法告訴我們that指上文，而this指下文。句意是“他們不得不考慮的最重要的問題之一就是公眾健康的問題”。