题目内容：

Courage is knowing what not to fear .what后省略了什么?为什么有to

优质解答

如果楼主理解 ...know what to do / know what to fear,那么自然能够理解...know what not to do / know what not to fear.因为not to fear 只是不定式to fear的否定形式而已,就像You had better do sth与You'd better not do sth的关系一样.
【俊狼猎英】