16. What am I doing?17. Is Boris Petrov putting his exercise-book on the table?18. Who's your friend?19. Who's this man?20. Are these men factory workers or engineers?21. Who's this girl?22. Where are our books?23. Whose books are these?24. Whose exercise-books are these?25. What kind of room's this?26. What kind of pencil's this?27.What kind of pen's that?