dare作为情态动词,必须和省略to 的动词不定式合成谓语.一般用于疑问句和否定句.没有三单和过去是变化.Dare he climb trees?He daren't climb trees.
dare作为实意动词,常＋to do做宾语.此时有三单和过去式变化.但只用于肯定句.He dares to climb trees.He dared to climb trees years ago.