13. D. with
14. A. serious: nghiêm trọng
15. B. natural
16. B. pollutants: chất ô nhiễm
17. D. interference: sự can thiệp
18. A. offspring: con cháu
19. A. established = set up: thành lập
20. A. extinct: tuyệt chủng
21. D. provided = supply: cung cấp
22. B. environment: môi trường
23. C. destroy
24. D. whose
25. C. on which we depend. "depend on": phụ thuộc vào
26. D. that. "The farmer and their cattle" => chỉ cả người và vật => "that"
27. A. with whom I used to work
28 C. which
29. C. which

I. Some sentences have a word that should not be there. Write the word at the end.
2. Correct.
3. it.
4. her
5. them

II. Write all the relative pronouns possible to complete each sentences
1. which. "on which" thay thế cho "the door".
2. what. "to what": theo những gì
3. which. "this table" => which
4. why. "reason why": lí do tại sao
5. whose
6. which. "famous temple" => which
7. which. "of which"
8. who. "Tom" => who
9. who. "My bother" => who
10. which. "the coffee" => which