What did you （do） last weekend?括号里面为什么要用do?

What did you do? What did you do? what did you.do what did you do What did you do what did you do yesterday? What did you do yesterday? what did you do today? What did you do there what did you do here? What did you do with What did you do next? what do you do?what did you do?what do you did?怎么区别, what did you do 和 what you did 的区别 What other things did you do?(改为同义句）（ ）（ ）did you do? when did you do和what did you do 区别 What did you do yesterday?(小短文） what did you do when the lights went out?）