例句 : When you enter a building, be sure to look behind you and hold the door open for someone coming through the same door.It is a common courtesy in many cultures.

翻譯 : 當你進入一個大樓時，一定要看看你的後方並未通過同一扇門的人把門開著。在很多文化中，這是一個普通的禮儀。