EXERCISE 3: Choose the underlined part in each sentence (A, B,C, or D ) that needs correcting. 1. After Mrs. Wang had returned to her house from work, she A B C was cooking dinner. D 2. Jimmy threw the ball high in the air, and Betty catching it when it came down. A B C D 3. Linda has worn her new yellow dress only once since she buys it. A B C D 4. Last week Mark told me that he got very bored with his present job A B and is looking for a new one. C D 5. Having fed the dog, he was sat down to his own meal. A B C D 6. When I turned on my computer, I was shocked to find some junk mail, A B and I delete it all. C D 7. They are going to have to leave soon and so do we. A B C D 8. The boss laughed when the secretary has told him that she really A B needed a pay rise. C D 9. The telephone rang several times and then stop before I could answer it. A B C D 10. Debbie, whose father is an excellent tennis player, has been playing A B C tennis since ten years. D 11. I have seen lots of interesting places when I went on holiday last summer. A B C D 12. When my cat heard a noise in the bushes, she stopped moving and listen intently. A B C D 13. I think it’s time you change your way of living. A B C D 14. Roger felt the outside of his pocket to make sure his wallet is still there. A B C D 15. When I’m shopping in the supermarket, I ran into an old friend who I A B hadn’t met for five years. C D 16. The police arrested the man while he is having dinner in a restaurant. A B C D 17. Peter and Wendy first met in 2006, and they are married for three years now. A B C D 18. Some people are believing there is life on other planets. A B C D 19. Recently, the island of Hawaii had been the subject of A B intensive research on the occurrence of earthquakes. C D 20. Every morning, the sun shines in my bedroom window and waking A B C me up. D 21. The man died as a result of falling asleep while he drives. A B C D 22. I haven’t finished the report yet, but by the time you return I A B C will certainly complete it. D 23. Caroline has worn her new yellow dress only once since she buys it. A B C D 24. We’ll be cycled to Hoa’s village at this time next Sunday. A B C D 25. What will you do when your friends won’t come ? A B C D 26. Someone was knocking at the door when I was doing the washing up. A B C D 27. My friend didn’t drink any beer since we came to live here. A B C D 28. We have written to each other when we were in primary school. A B C D 29. After breakfast, I‘m gone to walk to school with my friends. A B C D 30. Did he go to the pop concert next weekend for a change? A B C D

Phương pháp làm bài:
- Đầu tiên, đọc và hiểu câu hỏi.
- Tiếp theo, đọc từng câu trong bài để phát hiện và sửa lỗi sai.
- Chú ý đến từ/ngữ pháp, cấu trúc câu, thì, chủ ngữ, động từ, các từ kết hợp với nhau trong câu.
- Chọn đáp án (A, B, C, D) mà bạn cho là đúng.
- Kiểm tra lại câu đã sửa và chọn đáp án đúng nhất.

Câu trả lời:
1. Correct: was cooking dinner.
2. Change "catching" to "caught": and Betty caught it when it came down.
3. Change "buys" to "bought": Linda has worn her new yellow dress only once since she bought it.
4. Change "got" to "was getting": Last week Mark told me that he was getting very bored with his present job.
5. Change "sat" to "sitting": Having fed the dog, he was sitting down to his own meal.
6. Change "delete" to "deleted": When I turned on my computer, I was shocked to find some junk mail, and I deleted it all.
7. Change "so" to "neither": They are going to have to leave soon and so do we.
8. Change "has told" to "told": The boss laughed when the secretary told him that she really needed a pay rise.
9. Change "stop" to "stopped": The telephone rang several times and then stopped before I could answer it.
10. Change "since" to "for": Debbie, whose father is an excellent tennis player, has been playing tennis for ten years.
11. Change "went" to "go": I have seen lots of interesting places when I go on holiday last summer.
12. Change "listen" to "listening": When my cat heard a noise in the bushes, she stopped moving and listened intently.
13. Change "change" to "changed": I think it's time you changed your way of living.
14. Change "is" to "was": Roger felt the outside of his pocket to make sure his wallet was still there.
15. Change "ran" to "run": When I'm shopping in the supermarket, I run into an old friend who I hadn't met for five years.
16. Change "is having" to "was having": The police arrested the man while he was having dinner in a restaurant.
17. Change "are married" to "have been married": Peter and Wendy first met in 2006, and they have been married for three years now.
18. Change "are believing" to "believe": Some people believe there is life on other planets.
19. Remove "the": Recently, the island of Hawaii had been the subject of intensive research on the occurrence of earthquakes.
20. Change "waking" to "wakes": Every morning, the sun shines in my bedroom window and wakes me up.
21. Change "drives" to "drove": The man died as a result of falling asleep while he drove.
22. Change "will" to "would": I haven't finished the report yet, but by the time you return I would certainly complete it.
23. Change "buys" to "bought": Caroline has worn her new yellow dress only once since she bought it.
24. Change "cycled" to "cycle": We'll cycle to Hoa's village at this time next Sunday.
25. Change "won't" to "don't": What will you do when your friends don't come?
26. Change "doing" to "did": Someone was knocking at the door when I did the washing up.
27. Change "drink" to "has drunk": My friend hasn't drunk any beer since we came to live here.
28. Change "were" to "were writing": We were writing to each other when we were in primary school.
29. Change "gone" to "go": After breakfast, I go to walk to school with my friends.
30. Change "next" to "this": Did he go to the pop concert this weekend for a change?

8. The boss laughed when the secretary has told him that she really needed a pay rise.

4. Last week Mark told me that he got very bored with his present job and is looking for a new one.

1. After Mrs. Wang had returned to her house from work, she was cooking dinner.

Để giải câu hỏi này, ta cần biết rằng H2SO4 là công thức hóa học của axit sulfuric, còn FE(NO3)2 là công thức hóa học của muối sắt (II) nitrat.

Phân loại hóa chất dựa vào thành phần và cấu trúc hóa học. Dựa vào công thức đã cho, ta có thể xác định phân loại của chúng.

Sử dụng phân loại axit và muối, ta có:
- H2SO4: H2SO4 là một axit, có công thức tổng quát là HX, với X là nguyên tố đi kèm. Vì vậy, H2SO4 thuộc phân loại axit.
- FE(NO3)2: FE(NO3)2 là muối, với nguyên tử sắt (Fe) thay thế cho nguyên tố hiđro (H) trong axit nitric (HNO3). Vì vậy, FE(NO3)2 thuộc phân loại muối.

Vậy, H2SO4 thuộc phân loại axit, còn FE(NO3)2 thuộc phân loại muối.