Ppbv
abbr. parts per billion by volume 十亿分体积比
🗣️ 情景例句
What's up?
有什么事？
Can I use the lift?
我能用电梯吗？
It was a Sunday in May. My brother and I had decided to go off for a long walk while we were staying with my grandparents in the French countryside.
5月的一个星期天，我和弟弟决定去远足。当时我们住在法国乡下的祖父母家中。