考研英语|长难句打卡练习Day8

The brain finds it best to keep smell receptors available for unfamiliarand emergency signals such as the smell of smoke, which might indicatethe danger of fire.

本句是个复合句，逗号前面部分为主句，后面是which引导的非限制性定语从句。主句的主干为The brain finds it best to keep... 即“find it + adj+ todo”结构，在“findit+adj+to do”结构中，it作为形式宾语，真正的宾语是后面的不定式短语，翻译为“发现做………是怎样的”