Ppm.
[医] 兆比率(百万分之几)
🗣️ 情景例句
I can see that you've done this before.
我发觉你曾干过此事。
How much is it by air mail?
航空信要多少钱？
Thirteen is not as good as one, but it's better than nothing.
“13下是不如1下好，但总比1下也不敲强。