rarefied air 稀薄的空气
rarefy the atmosphere 使大气稀薄
rarefy the essence 使本质精炼
A: Why is it harder to breathe up here?
A：为什么在这里呼吸变得更加困难？
B: Because the air starts to rarefy at high altitudes.
B：因为在高海拔地区，空气会开始变得稀薄。
1) 使稀薄
2) 使变稀
3) 使精炼
1. 使稀薄，使变稀
verb
1. To make something less dense or thin, especially a gas or liquid.
Synonym: dilute, attenuate