Here are the suitable prepositions to fill in the blanks:

3. **to**
4. **for**
5. **in**
6. **to**
7. **as**
8. **after**
9. **on**
10. **to**

So the completed sentences would be:

3. Carpentry isn’t right **to** my street. I’d rather pay someone else to do it.
4. Could you help me look **for** my contact lens?
5. What do you usually do **in** your leisure time?
6. A lot of kids nowadays have become addicted **to** surfing the net.
7. We work **as** volunteers for an animal protection organization.
8. He spends most of his free time looking **after** the garden.
9. Today, teenagers rely **on** technology more than in the past.
10. Surfing the Net too many hours can be harmful **to** your health.