used to do改为否定句
问题描述：
used to do改为否定句
Jack used to live in a small village with his grandpa.改为否定句
印象里不是应该在used和to之间加not吗?
为什么答案是didn't use to
答
used to do 有两种否定形式
1.usedn't to do （used not to do）
2.didn't use to do
疑问也是两种
Used……?
Did……?
所以都可以,不过didn't use to 更加常见