◎ 题干
We can hear sound because our earth is surrounded by thick air _____ sound can travel.
[     ]
A. in that  
B. by which  
C. with which  
D. through which
◎ 答案
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“We can hear sound because our earth is surrounded by thick air _____ sound can travel.[ ]A. in that B. by which C. with which D. through which…”主要考查了你对  【关系代词】【介词和介词短语】【限制性定语从句】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。