怎样区分need是情态动词还是实义动词?

问题描述:

怎样区分need是情态动词还是实义动词?

need 实义动词,有人称和时态的变化.后接不定式.比如:
He doesn't need to do this work.
need情态动词,无人称时态的变化,后接动词原形.