Here are the sentences with the verbs in the correct form:

3. I studied German at school, but **I have forgotten** most of it now. (I / forget)

4. The police **arrested** three people, but later they let them go. (arrest)

5. What do you think of my English? Do you think **it has improved**? (it / improve)

6. Are you ready to go? **Have you finished** your coffee? (you / finish)

7. **I applied** for a job as a tour guide, but I wasn’t successful. (I / apply)

8. Where’s my bike? **It was** outside the house, but it’s not there now. (it / be)

9. Quick! We need to call an ambulance. **There has been** an accident. (there / be)

10. A: I’ve found my phone.
B: Oh, good. Where **did you find** it? (you / find)
A: **It was** at the bottom of my bag. (It / be)

11. A: Ben won’t be able to play tennis for a while. **He has broken** his arm. (He / break)
B: Oh. How **did that happen**? (that / happen)
A: **He fell** off a ladder. (He / fall)