want to:动词不定式,后面加动词,表示想做某事,

如I want to watch TV.我想看电视.

want：及物动词,后面加名词,表示想要某物,

如I want the bigger apple.我想要那个大点的苹果.

need：及物动词,后面加名词,表示想要某物,

如I need money.我需要钱.

need to：动词不定式,后面加动词,表示应该做某事,

如I need to do homework now.我现在要做作业了.

want在英语中通常是后面跟动词不定式做宾语，譬如want to do sth.