Passive air defense
un. 消极防空
🧩 词语组成解析
air
[ɛə]
n. 天空;气氛;空运;（简单易记的）曲调;
vt.& vi. 晾晒;烘干;播送;广播;
vt. 使房间通风， 透气;
🗣️ 情景例句
I have approximately three-year experience using a computer.
我有大约三年操作电脑的经验。
Why are you so lazy?
你为什么这样懒惰？
I have to raise some issues which may be embarrassing.
我必须提出一些比较尴尬的问题。