be used to do sth.否定形式是什么?

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。