Ppbv
abbr. parts per billion by volume 十亿分体积比
🗣️ 情景例句
I'm sorry you have to leave so soon.
很遗憾你不能多呆会儿。
Did you repair this yourself?
你自己亲自修理这个？
Well done, everyone! she smiled.
“你们个个表现出色！”她笑了