半情态动词used to在一般疑问句、否定句、附加问句中，可有两种变化形式：

【一般疑问句】

Did you use to go to the same school as your brother?

Used you to go to the same school as your brother?

你过去和你哥哥去同一所学校上学吗？

【否定句】

I usedn't to go there.

I didn't use to go there.

我过去不常去那里。

【否定疑问句】

Usedn't you to be interested in the theatre?

Didn't you use to be interested in the theatre?

你过去不对戏剧感兴趣吗？

【反意疑问句】

She used to be very fat, didn't she?

She used to be very fat, usedn't she?

她过去很胖，不是吗？

Yes, she did.

Yes, she used to.

是的，她过去是。