Air, or _____ is called atmosphere, surrounds the whole earth. - 题库学习平台

Air, or _____ is called atmosphere, surrounds the whole earth.
A、it
B、that
C、which
D、what
【正确答案】：D
【题目解析】：本题测试连词的用法。本句为主语从句，what在从句中做主语。

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