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
Between now and tomorrow
从现在起到明天
Books, like friends, should be few and well chosen.
书籍如朋友，应该少而精。
and if a single curved glass would distort nature, how much more would a pair of them?
何况一片曲面镜就可歪曲自然，那么伽利略的两片曲面镜对自然的歪曲又该多大呢？