Question

used to的否定式是什么样的啊？

Answer 1

used to 用於叙述过去的习惯，比如说 I used to go to the park with my grandma.
我以前常常和我的奶奶去公园。(但现在没有了)

to get used + to / be used to 后面需接V-ing
表示习惯於某事，后面的 to是介系词，所以接在兔之后的动词必须变成动名词的型态，比如说
1. I get used to listening to the music before I go to bed.
我习惯在睡前听音乐。
2. I was used to living in the city. 我习惯住在都市.

否定:
例: People didn't use to live in apartments. 人们以前不住在公寓里. (表过去没有住公寓的习惯)
I wasn't uesd to living in the country. 我不习惯住在乡村.

Answer 2

used to其实相当于一个副词的作用，表示过去常常，不存在否定的形式。

Answer 3

usen't to 或 didn't use to