1. (-) They weren't in Rio last summer.

(?) Were they in Rio last summer?

2. (-) We didn't do our exercise this morning.

(?) Did we do our exercise this morning?

3(-) My parents didn't come to visit me last July.

(?) Did my parents come to visit me last July?

4.(-) The hotel wasn't very expensive.

(?) Was the hotel very expensive?

1. They were not in Rio last summer.
   (Were they in Rio last summer?)
2. She was not my boss.
   (Was she my boss?)
3. I was at the concert last Sunday.
   (I wasn't at the concert last Sunday.)
   (Was I at the concert last Sunday?)
4. The hotel was not very expensive.
   (Was the hotel very expensive?)