1:There used to be a bookshelf here . ( There be句型)
2:It used to be said that… ( 固定句型,过去常说)
3:It used to doing something ( 过去习惯做某事)
4:Used you to go to the park ? ( used一般疑问句直接提前used)
5:Where used you to do ( used特殊疑问句直接提前used)
望采纳,谢谢!