Pentafluoroguanidine
五氟化胍
🗣️ 情景例句
Lacks courtesy is ill-mannered.
不礼貌，举止不当。
A lazy youth, a lousy age.
少壮不努力，老大徒伤悲。
A run-down watch is still a watch and can be rewound.
手表停了依然是只手表，还可以重上好发条。