Prodan
氟硅酸钠
🗣️ 情景例句
I know.
我知道。
Where were you on Tuesday?
星期二你在哪里？
We have just moved into a new house and I have been working hard all morning.
我们刚刚搬进一所新房子，我辛辛苦苦地干了整整一个上午。