Just rememble,______ fire,ring the alarm for help.

问题描述:

Just rememble,______ fire,ring the alarm for help.
A.in case of B.on the occasion of
请告诉我B为什么不对?B是“值此之际,在...期间”意思.放到这里貌似没错呀.

in case of fire 如果火灾发生,这个本身是个句子 类似第2楼说 俗成
IN CASE OF FIRE,KEEP YOUR COOL
IN CASE OF FIRE,KNOW YOUR WAY OUT
等等句子,在警示板上就是这样表示.
而 on the occasion of
on the occasion of one's graduation
on the occasion of someone death