Ppb
[化] 十亿分率
🗣️ 情景例句
He should just about get by in the exam.
他这次考试还能勉强及格。
My phone was out of order.
我的电话坏了。
If explosives are used, vibrations will cause the roof of the mine to collapse.
如果用炸药爆破，震动会引起矿顶塌落。