1.need 做情态动词的时候,无人称或数的变化,后接动词原形,一般用于否定句和疑问句中,不用在肯定句.如：You needn't go there.Need I go with you?
2.need 作为行为动词有人称和数的变化,后面可接名词,代词、动名词及带to 的动词不定式；可用于肯定句、疑问句和否定句中.如：.
She needs help.(接名词)
Your hair needs cutting.(动名词)
You don't need to go there.（动词不定式）
Does she need to go with you?