Ppbv
abbr. parts per billion by volume 十亿分体积比
🗣️ 情景例句
It was his first date in two years.
这是他两年来第一次约会。
What are you speaking about?
你正在谈什么？
I wonder if it is possible to arrange shopping for us.
我想能否在我们访问结束时为我们安排一点时间购物。