have to所在的句子在进行句型转换时要借助什么

have to所在的句子在进行句型转换时要借助于助动词 do ,does ,did .
例如：
I have to sweep the floor.
---I don't have to sweep the floor.
She has to finish her homework .
---Does she have to finish her homework
They had to water the flowers.
---Did they have to water the flowers?

借助于助动词do.

助动词 do ，does ，did .
情态动词can,may mast等