I used to …

Question 1

Dave used to work in a factory =

Answer 1

He workED in a factory BEFORE, but he DOESN’T work there NOW

Question 2

You can say I used to work … / she used to have … / they used to be … etc. :

Answer 2

…They used to live in the same street as us, so
we used to see them a lot. But we don’t see
them much these days.
…Helen used to have a piano, but she sold it a
few years ago.

Question 3

The question is

Answer 3

DID you use to … ?

…Where DID you use to live before you came here?