i don't need to finish 为什么加to,need否定还用to?

问题描述:

i don't need to finish 为什么加to,need否定还用to?

need可以当实义动词,就是用need to do sth,否定就用助动词啊
need当情态动词的时候,后面用原形,否定直接用needn't
上面的句子也可以是 I needn't finish.