Ppbv
abbr. parts per billion by volume 十亿分体积比
🗣️ 情景例句
I never expected you would do such a fantastic job.
我从没想过你会做得这么出色！
Who is it? Come down.
是谁？下来。
Ever since, people have had difficulty in deciding whether the craft should be ranged among ships,
自那以后，人们很难决定是否应该将这种运载工具列为轮船、