第一句不对,应该把are改成is,因为who作主语时应该是单数形式
Whose bag is heavier than mine?
Your bag isn't heavier than mine.
Which boy is David?Your bag is heavier than mine.改为一般疑问句那个第一句原题是The girls swims faster than the boys.对The girls 提问The boy with a small mouth is David.with a small mouth划线部分， 对划线部分提问Is your bag heavier than mine?Who swims faster than the boys?The boy with a small mouth is David.with a small mouth划线部分， 对划线部分提问Which boy is David?哪一个男孩是大卫？Your bag is heavier than mine.改为一般疑问句Is your bag heavier than mine?mine 难道不要改成yours 吗反过来问的啊不用，因为这句话原句中就是说你的书包比我的重，变成一般疑问句就是问 你的书包比我的重吗？那么对划线部分提问的要改吗你把那个句子再写一遍，太多，我不知道是哪个了