\(a,\frac{97^3+83^3}{180}-97.83\)

\(=\frac{\left(97+83\right)\left(97^2-97.83+83^2\right)}{180}-97.83\)

\(=\frac{180\left(97^2-97.83+83^2\right)}{180}-97.83\)

\(=97^2-97.83+83^2-97.83\)

\(=97^2+83^2-2.97.83\)

\(=\left(97-83\right)^2\)

\(=14^2=196\)

I .

1 . D

2. B

3. C

4. C

5.A

6. A

7. D

8. A

9. C

10. D

II.

1, B

2,A

3.D

4.D

5. C

6. B

7. C

8. B

9. B

10. D

11. D

12. C

13. B

14. B

15. B

16. A

17. D

18. D

19. C

20. C

21. C

22. B

23. C

24. B

25. B

26. B

27. B

28. C

29. C

30. D

31. B

32. A

33. C

34. D\

35. A

36. C

37. C

38. B

39. B

40.B

1. It's ages since I played football.

2. I haven't gone to Ha Noi for over 4 years.

3. It's the first time she has spoken Japanese.

4.She hasn't driven a car before.

5. I last heard from in July.

6. It's years since I stayed in a hotel.

7. He hasn't gone home for 2 years.

1. c

2. d

3. d

4. a