must
have to 表示客观的需要
eg.Tom,come out to play with us.
Sorry,my mom said i have to finish my homework first.
eg.Do you have to leave now?
yes,i must
eg Do i have to eat it up,mom?
no,you needn't
参考资料：自己的回答和Dr.eye译典通字典
回答者：南山阿辉 - 同进士出身 六级 12-25 19:38
hao ,但太多了