用于表示“需要,必要”之意.做情态动词时,仅用于否定句和疑问句,只有现在时,过去式要用needn't have,疑问式用need+人称?,否定式用need not(即needn't）,
1．—Need we leave soon?
—Yes,you must.(No,you needn't)
2．You needn't have hurried.
(=It was not necessary for you to hurry,but you did).你当时不必这么匆忙.
3.He needs to see a doctor.(need to do)汉语