10.Some people viewed the findings with caution,noting that a cause-and-effect relationship...

题目

10.Some people viewed the findings with caution,noting that a cause-and-effect relationship...
Some people viewed the findings with caution,noting that a cause-and-effect relationship between passive somking and cancer remains____.
A.to have shown
B.to be shown
C.to have been shown
D.being shown
为什么选B,我基础不好,请讲详细点,分析考点及解题思路

答案

首先理通整个句子：有些人仍然对这个结果持有观望态度,因为还没有发现被动吸烟和癌症有直接因果关系的证据.这里remains to be seen 对应的就是中文里“还没有发现”还没有发现是以人为主语而这个英文句子中那个“被...