【例句】(2005完形)

　　The explanation for insensitivity to smell seems to be that brain finds it inefficient to keep all smell receptors working all the time but can create new receptors if necessary.

　　【解题技巧】划出谓语 - 划出从句引导词 - 划出并列连词If (it is) necessary, …

　　【参考译文】对气味不敏感的解释似乎是大脑发现让所有的气味感受器一直工作效率太低，但是在需要时大脑仍可以产生新的感受器。