11. The child will die unless someone helps him.

=> Unless = if not

12. If you took good care of the car, it wouldn't break down very often.

=> Đây là câu điều kiện (conditions). If này là if loại 2- điều kiện không có thật ở hiện tại. (Tức là hiện tại bạn ko chăm sóc xe tốt nên nó dễ hư)

13. If she were not so busy, she could go to the party.

=> Loại câu như trên nha.

14. Brian said that his parents had worked there for 10 years.

=> Câu trần thuật (reported speech). Ở câu gốc là hiện tại hoàn thành thì mình lùi thì thành quá khứ hoàn thành. Và here phải chuyển thành there.

15. Peterson told me that he didn't collect/ haven't collected his children from school the previous day.

=> Loại câu như 14. Yesterday đổi thành previous day hoặc the day before. Câu gốc quá khứ -> giữ nguyên hoặc lùi về QK hoàn thành

11.The child will die unless someone helps him

12.If you took care of the car, it wouldn't break down very often.

13.If she was not busy, she would come to the party

14.Brian said that his parents had worked here for 10 years

15.Peterson told me that he had not collected his children from school the previous day

16.Lan asked her brother whether he was free that night

17.The policeman asked me where I came from

18.John's friend congratulated on having passed the driving test

19.My teacher advised me to take the final test

20.The woman who phoned me yesterday was very polite

21.He failed the exam, which makes his parents upset

22.Can you show me the photos which you took during your vaction?

23.That is the project which my uncle is interested in