The explanation for insensitivity to smell seems tobe that brain finds it
inefficient to keep all smellreceptors working all the time but can create
newreceptors if necessary. 译文:嗅觉迟钝似乎可以解释为,大脑无法保证所有的嗅觉接收器一直处于工作之中,却可以在必要时创造出新的接收器。 点睛:that引导的是表语从句,其中finds和can create为并列的谓语动词。it为形式宾语,真正的宾语是to keep…allthe
time。现在分词短语working all the time为smell receptors的补足语。if necessary为省略句,其完整形式应为if
it is necessary。