Wood furniture does not depreciate in value _____.

Wood furniture does not depreciate in value _____.
A、if they are handle properly and protected properly
B、unless handling and protecting properly
C、if properly handled and protected
D、unless for all its handling and protection
【正确答案】：C
【题目解析】：if意为“如果”，而unless意为“除非”，相当于if…not。根据句意可知，应选择引导的条件状语从句。当引导的从句与主句的主语相同时，可以用“if＋分词”结构。