你问错了,
应该是used to do 的否定
used to do sth.句型表示“过去常常,过去习惯.”表示过去的某种习惯(过去经常反复发生的动作或状态).
e.g.I used to live there when I was a child.
n
否定式：used not to do sth.
口语中：didn’t use to do sth.
(used not可缩写为usedn’t或usen’t.)
e.g.I used not to live there when I was a child.
I didn’t use to live there when I was a child.
疑问句：used sb.to do sth.
Did sb.use to do sth.
e.g.Used you to live there when you was a child.
Did you use to live there when you was a child?
used to do sth.与be used to (doing) sth.的区别
1.used to do sth.“过去总做某事”(现在不做了)只用于过去时态.
e.g.He used to get up early.
2.be used to (doing) sth.表“习惯于做某事”,可用于现在、过去、将来的多种时态,be可以用become,get等来代替,此处to是介词.