6.(-) We aren't working on our duty.
   (?) Are we working on our duty?
7.(-) Mary isn't sleeping in her room.
   (?) Is Mary sleeping in her room?
8.(-)They aren't  playing volleyball.
   (?)Are they playing volleyball?
9.(-)Minh isn't doing his homework.
   (?)Is Minh doing his homework?
10.(-)My parents aren't talking in the living room.
     (?)Are my parents talking in the living room?