Circle the best answer for each sentence.

6. Nuclear energy is unlimited but it is very _________to human beings and the environment.

A. extinct B.released C. endangered D. dangerous

7. The music _________ you are listening sounds really interesting.

A. which B.to that C. to which D. to whom

9. Dinosaurs became _________ millions of years ago.

A. develop B.extinct C. increase D. decrease

10. She is the woman _______ I told you.

A. to whom B. with whom C. about which D.about whom

13. It was the kind of accident for _________nobody was really to blame.

A. who B. whom C. that D.which

14. He is the singer about _________ I often tell you.

A. whom B. that C. him D. who

15. The 1^stAsian Games _________ in New delhi, India in 1951.

A. were held B. are held C. was held D. is held

16. Walkers can unwittingly damage the fragile environment _________.

A. that the birds live B. where the birds live in

C. which live the birds D. in which the birds live

17. Oil, coal, and natural gas are _________fuels made from decayed material from animals or plants.

A. Fossil B.Smokeless C.Unleaded D.Solid

18. Only six _________ were played in the first Asian Games.

A. athletes B. sports events C. coaches D. spectators

19. ________ heat comes from deep inside the earth.

A. Geothermal B. Solar C. Nuclear D. Hydro

20. The sun, water and the wind are other_________sources of energy.

A. alternative B. replace C. electric D. useless

21. They won two gold_________in bodybuilding and billiards.

A. degrees B. awards C. prizes D. medals

22. Although there are some disadvantages, the potential of alternative sources of energy_________ great.

A. are B. is C. have been D. was

23. Thousands of national parks all over the world_________ to protect endangered animals.

A. has been established B. has been establishing

C. have been established D. have been establishing

24. The quality of athletes, officials and sports facilities _________ through time.

A. is developing also B. has also been developing

C. have also been developing D. are developing

25. They work in a hospital _________ by the government.

A. which sponsored B. was sponsored C. sponsored D. sponsoring

28. Many efforts have been made to protect ____ nature.

A. danger B. dangerous C. endanger D. endangered

tìm giới hạn \(\lim\limits_{x\rightarrow-\infty}\dfrac{\sqrt{4x^2+2x-1}-x}{3x-2}\)