=>
29. hadn't -> didn't
30. thiếu đề
31. had gone -> would have gone
32. joyfully -> joyfulness
II/
33. polluted
34. independently
35. thiếu đề
36. contamination
37. I haven't visited Thanh for 3 years.
38. Beautiful postcards are often sent us by our friends.
39. It took her 2 days to tidy her room last week.
40. If I had time, I could visit my friends.
41. If this watch weren't expensive, I could buy it.
42. If I had been hungry, I would have eaten something.
43. English is spoken in this club.
44. All homework was done by Minh yesterday.