Ppm.
[医] 兆比率(百万分之几)
🗣️ 情景例句
Scientific discoveries are ofter applied to industrial production methods.
科学新发现常应用于工业生产的方法。
I got your back.
放心！
Fortunately, a pilot saw the signal and sent a message by radio to the nearest town.
幸运得很，一位飞行员看到这个信号，用无线电给最近的城镇发了报。