A.what does your mother do?和B.what do your parents do?中的your都是单三,但为什么AB句中的助动词不一样呢?请大家回答得完整点，因为我刚入门，有点晕！也可以举例大家在回答我一个问题：什么情况下

What does your mother what does your borther --------- does your best friend look like a.what b.how ------- does your best friend look like a.what b.how what does your brother ( ) A have B has What does your mother do?She´s a What does your sister do?She is a ____(violin). what does your mother do? What does your father work? what does your mother do? what does your family like What time does your school What does your sister do? What does your parents do? what does your grandfather have? what does your grandfather do? What does your father?是什么意思 a,we,have,picnic,it,if,mot,does,rain,tomorrow,shall连词成句