Here are the best answers for Exercise 8:

1. **B. on** (Kelly is keen on comedies.)
2. **D. at** (Why are you interested at doing DIY projects?)
3. **A. detests** (Sue detests eating durian...)
4. **D. useful** (Do you think learning languages are useful for students?)
5. **C. am** (I feel am when I do leisure activities in my free time.)
6. **C. relaxing** (relaxing)
7. **A. text** (We like text friends every day.)
8. **C. spare** (What do you like doing in your spare time?)
9. **A. free** (Kim would prefer free at home on the weekend.)
10. **B. staying** (I think I will be able to stay my French.)

For Exercise 9:

1. **C. improving**
2. **A. spend**
3. **D. surfing**
4. **C. making**

Let me know if you need anything else!