题目内容：
In practice, this is an advantage to the aeroplane, which is already at a good height when it rea-ches the polar region and so does not to chmb, while at the same time cold air keeps the clouds down low. (Passage 1 )参考答案：
答案解析：
简答题：In practice, this is an advantage to the aeroplane, which is
- 题目分类：成人英语三级
- 题目类型：简答题
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