【题目】This kind of seafood is likely to go bad _____ it is treated immediately after it is caught from the sea.
A. as B. unless
C. since D. when
在线课程【答案】B
【解析】
考查连状语从句。句意：这种海产品很容易变质，除非一打捞上来就好好处理。分析句子可知，it is treated immediately作条件状语从句修饰主句，其逻辑关系属于if not，故选B。