24. C (several times → HTHT)
25. A (3 times this year → HTHT)
26. D (HTHT since QKD)
27. C (just; vế sau QKD → QKHT)
28. D (vế sau QKD → QKHT)
29. D (QKHT by the time QKD)
30. B
B.
31. D → playing
32. A → had eaten
33. A → were you doing
34. D → had already left
35. A → had known
36. A → dissapeared
37. D → cooked
38. C → had seen
39. B → had graduated
40. B → has been
C.
41. D - 42. A - 43. B - 44. C - 45. A