Question

【题目】Many young people in the West are expected to leave __________ could be life's most important decision—marriage—almost entirely up to luck.

A. as B. that C. which D. what

Answer 1

【答案】D

【解析】句意：西方的很多年轻人期望把可能是一生中最重要的决定----婚姻几乎完全寄托于运气。What引导宾语从句,而且在从句中做主语. marriage“婚姻”为leave后面的宾语（从句）的同位语，解释该宾语从句what could be life's most important decision的所指内容，即“婚姻即为一生中可能最重要的决定”。

该宾语从句明显缺失一个表sth的主语，所以必须用what来代替并引导该从句。