【题目】Vehicle accidents have claimed many deaths in the past few years. _________ more action is taken, the problem will get dramatically worse.
A. IfB. Unless C. After D. When
在线课程【答案】B
【解析】考查状语从句句意：交通事故过去一些年中夺取了许多人的生命，除非采取更多的措施否则问题将更加严重。依照句意此处表示的是“除非”之意，故选B项适合。