Perfluoroethylene
[机] 四氟乙烯
🗣️ 情景例句
Do we have to pre-book tours, or can we get them on site?
我们必须预定行程， 还是到那个地方再说？
Sweet discourse makes short days and nights.
言语投机恨时短。
I can't understand why he is being so selfish. He isn't usually like that.
我不明白他此刻怎么这么自私。他平时不这样。