these volleyballs are ($55).对括号部分提问 i need a pair of shoes f

1、These volleyballs are ($55).（对括号部分提问 ）
How much are these volleyballs?
2、I need a pair of shoes for school.（改为一般疑问句）
Do you need a pair of shoes for school?
3、We sell bags.（改为否定句）
We don't sell bags.