Ppbv
abbr. parts per billion by volume 十亿分体积比
🗣️ 情景例句
His wife just found out about his mistress.
他的妻子刚刚发现了他有外遇。
Excuse me, but may I ask a question?
对不起，我可以问个问题吗？
You're always welcome.
别客气。