Whenever you can, follow/ three R's/ conserve natural resources.

-> Whenever you can, follow the three R's to conserve natural resources.

(Bất cứ khi nào có thể, hãy tuân theo ba nguyên tắc R để bảo tồn tài nguyên thiên nhiên.)

38. A. water in rivers

39. D. use products again and again

40. A. fully use the washing machine

41. B. waste can be recycled and reused

42. C. recycling

43. C. Not until after midnight did the noise next door stop.

44. A. Phong said that he wanted to become a scientist.

45. C. I prefer watching television to reading newspapers.

46. C. If my friend had enough money, she could buy that dress.

47. A. Yesterday, a powerful earthquake caused lots of damage to property.

49. B. He has decided to go to work in a school in a quite remote area.

50. B. When the rescuers arrived, the whole family had already evacuated.

\(A>B\left(2\sqrt{x}+5\right)\)

\(\Rightarrow\dfrac{\sqrt{x}+2}{\sqrt{x}-5}>\dfrac{2\sqrt{x}+5}{\sqrt{x}-5}\) (1)

TH1: \(\sqrt{x}-5< 0\Rightarrow0\le x< 25\)

(1) \(\Rightarrow\sqrt{x}+2< 2\sqrt{x}+5\Rightarrow\sqrt{x}>-3\) (thoả mãn)

Mà x là số nguyên tố \(\Rightarrow x\in\left\{2;3;5;7;11;13;17;19;23\right\}\)

TH2: \(\sqrt{x}-5>0\Rightarrow x>25\)

(1) \(\Rightarrow\sqrt{x}+2>2\sqrt{x}+5\Rightarrow\sqrt{x}< -3\) (loại)

Vậy x \(\in\){2;3;5;7;11;13;17;19;23}

27. B. For ten years.

28. B. Yes, I’d love to.

29. B. reach

30. C. huge

31. C. appear

32. B. insignificant

33. B. inventors

34. A. carried

35. C. usage

36. D. of

37. C. keeping

11. C. destroyed

12. C. teacher

13. A. natural

14. B. homeless

15. B. aware of → aware

16. B. doing → do

17. C. attraction → attracts

18. C. talking

19. C. were provided

20. B. starts

21. A. to call

22. A. go usually

23. D. to see

24. A. exchange

25. B. stop

26. C. convenient

27. D. aquatic 

28. B. wounded 

29. C. permanent 

30. A. support 

31. C. in case of → in case 

32. A. weren't → wasn't 

33. B. pieces of the Earth's surface meet 

34. C. the Pacific coast of Asia 

35. A. changes in the Earth's surface 

36. A. lack of food 

37. D. how to predict earthquakes 

39. A. poisons

40. C. ways

41. C. by

42. C. environment

44. C. She has never been to the United Kingdom before.

45. A. Despite the weather was so bad, they decided to go camping.

47. I saw a thief when I was going shopping with my mother yesterday.

48. I didn’t read the news about the storm on newspapers, but I watched it on TV.

49. After he had cleaned his house, his friends came.

50. Since radioactive pollution is very dangerous, it can cause abnormal growth.

11. A. polluted phát âm /ɪd/, còn lại là /d/

12. A. insect phát âm /s/, còn lại là /z/

13. C. illustrate trọng âm âm 1, còn lại âm 2

14. D. affect trọng âm âm 2, còn lại âm 1

15. C. internet access 

16. A. don’t act 

17. A. because of 

18. D. flooded 

19. B. starts 

​20. B. shopaholic 

21. C. seeing 

22. B. environmental

23. A. arrives 

24. D. usually eat - are eating 

25. B. That’s shocking!

26. A. Sure. No problem. 

46. If I were you, I would recycle these plastic carrier bags.

47. Solar power has become more affordable, so more homeowners are installing solar panels.

48. When her mother was cooking, her little baby woke up and cried out.

49. We go to the discount store because it sells products at lower prices.

​50. Although my grandfather is very old, he is still young at heart.

38. C. after

39. D. polluted

40. A. chemical

41. C. reduce

42. B. led

43. B. I haven’t been to Bangkok before.

44. B. If I had enough money, I would buy seafood.

45. D. Because I don’t live with my mother, I can’t take care of her.