Here are the completed question tags for the exercise:

1. Sam is cooking in the kitchen, **isn't he**?
2. She wasn't sleeping, **was she**?
3. You speak Korean, **don't you**?
4. They can play volleyball, **can't they**?
5. He called you yesterday, **didn't he**?
6. He hadn't met this girl before, **had he**?
7. I shouldn’t smoke here, **should I**?
8. I am not speaking fast, **am I**?
9. Sue and Jim live in Hanoi, **don't they**?
10. She has just bought a new car, **hasn't she**?
11. You won’t say that again, **will you**?
12. Susan likes reading, **doesn't she**?
13. I am doing the gardening well, **aren't I**?
14. Kate gave you a new CD, **didn't she**?
15. There will be a new shopping mall in my town soon, **won't there**?

Feel free to ask if you need anything else!