IN or AT ???

如果係restroom前面既話, 咁就一定用in, 外國人唔會用at咁奇怪

e.g. i usually brush my teeth in the restroom

e.g. is there any mirror in the restroom?

不過at可以用o係restroom後面, 用黎接地方, 如商店, 公園, 屋企等等

e.g. have u been to the restroom at KFC?

e.g. the restroom at Roger's house is very big!

希望幫到你啦~

一般都是係用 in the restroom.

in the restroom ------ 一般的 room 都係用 in ...

in the restroom