Ppb
[化] 十亿分率
🗣️ 情景例句
Let's do lunch.
咱们做午饭吧。
Then I asked him if he knew anybody in New York .
然后我问他是否他在纽约认识人。
Ken gave up smoking two years ago. He'd been smoking for thirty years.
两年前肯戒了烟，之前他抽了三十年烟。