Does you sister have one?为什么不用your?

Does you sister have one?为什么不用your? Does she have a sister 为什么要用have不用has? Do you have an alarm clock?和Does your mother have a sister?怎 在句子中,有三单,却还用have,为什么?例:Does your sister have a pen? I have one book,one is for you and _______for your sister you have just come back your hometown为什么不用came Your sister have one?Your的前面应填什么 Does your father have a sister?(作否定回答) Does your sister have big eyes?做否定回答 "Does your sister have breakfast?"这句话对吗 DOES your sister have a computer作否定回答 have,your,ball,soccer,a,sister,does(?) (连词成句)