Hot the night air was, we slept deeply because we were so tired after the long journey.
A. although
B. however
C. while
D. as
网友回答
A. although
B. however
C. while
(答案→)D. as
解析：考查让步状语从句。ABCD四个选项均可以引导让步状语从句，但although，while引导让步状语从句时不使用倒装，as引导让步状语从句时要使用倒装，其结构为：表语+as+主语+谓语。故选D。However引导让步状语从句时其结构为However+形容词/副词+主语+谓语，故不能入选。