Make the sentences interrogative.

11. They went to St. Petersburg in summer. (Where...? When...? Who...?) 12. I'll listen to rock music at home. (Who...? Where...? What kind of...?) 13. Mary is going to learn English. (Who...? What language...?) 14. Sam and his girlfriend have come to stay with us this weekend. (Who...? Where...?) 15. There were five students in the class. (Where...? How many...?) 16. It usually takes me five minutes to get to the college. (How long...?) 17. My father is forty-seven years old. (Who...? How old...?) 18. This magazine costs fifteen rubles. (How much...? What...? What kind of...?) 19. They collected stamps. (What...? Who...?) 20. We have been friends with Vlad for quite a long time. (How long...?) 21. It is raining. 22. She likes cooking.23. He has taken a few pictures. 24. They don't know English. 25. We didn't go to a disco yesterday 26. She was my great friend. 27. Mike collected posters last year.