Answer:
1. What are you doing now?
2. Do you like glasses more?
3. Do you prefer the long or short dress?
4. Do you know these are my favorite albums?
5. Is it a finance department?
6. Is it a department of treasury you bought this year?
7. Did you bought a car this year?
8. Is it the most elegant shop in the center?
I'm not very good on explaining this but I'll give you an example or more than one.
Antonio y yo nos besamos.
Antonio and I kissed each other.
¿Os conocéis?
Do you all know each other?
Juan y María se casaron.
Juan and Maria got married (to each other).
Los estudiantes se ayudan.
The students help each other.
I hope it helped