Quaterisation
季铵化反应
🗣️ 情景例句
That's why the new community center is a good idea.
这就是为什么说新的社区中心是个好主意。
There are only two minutes left.
只剩两分钟了。
What on earth has happened to trouble you so?
到底发生什么事让您如此发愁？