Question

Even if there is no scientific proof        secondhand smoke causes cancer, there is no reason why nonsmokers should be forced to take this risk.

A. which                               B. that                                   C. when                             D. where

Answer

B

【解析】

试题分析:考查名词性从句。Proof后是同位语从句，说明proof的内容，而同位语从句意思完整，不缺少成分，所以用that引导，句意：即使没有科学证据表明吸二手烟会致癌，也没有理由让不吸烟的人们被迫去冒这种危险。

考点：考查名词性从句。