根据意思来, have to 的意思是不得不：
所以：
肯定回答 yes, you must; 否定回答： no, you needn't/ you don't have to.
Do i have to attend the wedding?
yes, you must/ no, you needn't
一般来说 这个是正解!你确定么？？怎么还是有不同的答案、、、确定，我问过外教，他说肯定回答可以是 yes, i do/ you must, 否定回答是，no, you don't have to