Question

What is even more important is______ the earth cooled down, water began to appear on its surface.

A．that

B．that as

C．which

D．which as

Answer 1

B

试题分析：考查表语从句。本题中的that引导的是表语从句，表语从句中有一个时间状语从句。句意：更重要的是随着地球的冷却下来，水也开始出现在地球的表面上了。故B正确。
点评：本题的难度在于从句中含有从句，that在从句中不充当任何成分，只起连接作用。本题的表语从句中含有as…的时间状语从句。