Ответ:

1. I won’t finish it on time unless you help me. (Conditional 1)

2. If I had another puncture, I would repair it. (Conditional 2)

3. If they were Japanese, they wouldn't speak Chinese. (Conditional 2)

4. If I saw a big spider in my house, I would scream loudly. (Conditional 2)

5. The hijackers would threaten us if they had a bomb. (Conditional 2)

6. You would have arrived earlier if you had caught a taxi. (Conditional 3)

7. Eric would have won the race if he had trained better. (Conditional 3)

8. Kevin will return to the office if his boss tells him so. (Conditional 1)

9. His mother would let him go to the party if he got good marks at the exam. (Conditional 2)

10. Maria’s friend would have enjoyed the concert if she had gone. (Conditional 3)