Fluoridizer
氟化剂, 氟化器
🗣️ 情景例句
How many classes are you taking this semester?
这学期你有多少课？
I'm hoping to spend a few days in the mountains.
我正在希望到在山上过一些天。
We arrived in London this afternoon.
我们是今天下午到达伦敦的。