问题
选择题
You have to wear a helmet and a life jacket for protection, just ___ you fall into the water.
A. in case C. unless
C. though D. as
答案
答案：A
题目分析:句意：你必须戴上头盔和救生衣用来保护自己，只是以防万一你掉入水里。A万一；B除非；C尽管；D因为，当……时候。根据句意可知戴这些东西的目的只是起防备作用，故答案选A。