alarm n.&v. /warn n.&v.

alarm的意思是“提醒，警告”，有使警觉，使做好准备的意思;warn的意思主要指“警告，告诫”，有事先告诉可能发生的事，警告说……的意思。

例：There were several alarms during the night but no actual air raid actually took place.

当夜，空袭警报拉响了数次，但并没有飞机来袭。

He warned us that the road was icy.

他警告我们说道路很滑。