-Must I hand in my homework now?该句子的must可以换成need吗?回答是不是一定要用need 来回答?

问句必须用 Must I, 回答是 you need/need not

Must强调 “必须”, Need是“需要”，意思或语气上还是略有区别的
回答：
must提问：肯定形式用 must 回答
否定形式用 needn't 回答
need提问：肯定形式用 need 回答
否定形式用 needn't 回答

换成need最好
---Need I hand in my homework now?
----Yes,you must/ No,you needn't
如果不换,也是应这样回答
-Must I hand in my homework now?
---Yes,you must / No,you needn't