is even more important is the earth cooled down, water began to appear on its surface.
A. When; that; when
B. What; whether; as
C. What; that; as
D. lt; whether; as
网友回答
A. When; that; when
B. What; whether; as
(答案→)C. What; that; as
D. lt; whether; as
解析：
这题考查从句的用法，第一空填what做主语从句，在主语从句中what做主语，第二空填that引导表语从句，在表语从句中，as是引导时间状语从句，句意是：甚至更重要的是：随着地球的冷却，水开始出现在表面。选C。