1. I was doing the washing up before my mother came home.

   • No correction needed.

2. It helps people who has suffered badly in wars or natural disasters.

   • Incorrect: has
   • Correction: who have suffered

3. In class, she suddenly remembered she didn't lock the door.

   • No correction needed.

4. Her mother ordered her do not go out with him the night before.

   • Incorrect: do not go out
   • Correction: not to go out

5. He said that he will pick me up at 8 am the following day.

   • Incorrect: will
   • Correction: would

6. The mayor apologized on having slept in an international summit and resigned afterwards.

   • Incorrect: on having slept
   • Correction: for sleeping

7. I haven’t heard from Maria since a long time.

   • Incorrect: since a long time
   • Correction: for a long time

8. The children were frightening by the thunder and lightning.

   • Incorrect: were frightening
   • Correction: were frightened

9. By the time she left the shop, she spent all of her money on clothes.

   • Incorrect: spent
   • Correction: had spent

10. The country has significant changed since we came here in 2007.

    • Incorrect: has significant changed
    • Correction: has significantly changed

11. My sister had worked in the bank for five years before she had been sent to Da Nang.

    • Incorrect: had worked and had been sent
    • Correction: worked and was sent

1. I was doing the washing up before my mother came home.

• Câu này đúng ngữ pháp. Không có lỗi sai.

2. it helps people who has suffered badly in wars or natural disasters.

• Lỗi sai: "has suffered"
• Sửa: "have suffered"
• Giải thích: Chủ ngữ là "people" (người) nên động từ phải chia ở dạng số nhiều.

3. In class, she suddenly remembered she didn't lock the door.

• Câu này đúng ngữ pháp. Không có lỗi sai.

4. Her mother ordered her do not go out with him the night before.

• Lỗi sai: "do not go"
• Sửa: "not to go"
• Giải thích: Sau động từ "ordered", ta dùng cấu trúc "to infinitive" (tính từ nguyên mẫu).

5. He said that he will pick me up at 8 am the following day.

• Lỗi sai: "will pick"
• Sửa: "would pick"
• Giải thích: Đây là câu tường thuật, động từ trong mệnh đề that clause lùi thì. "will" trong câu trực tiếp sẽ thành "would" trong câu gián tiếp.

6. The mayor apologized on having slept in an international summit and resigned afterwards.

• Lỗi sai: "on having slept"
• Sửa: "for having slept"
• Giải thích: Cụm từ "apologize for" có nghĩa là "xin lỗi vì".

7.1 haven't heard from the Maria since a long time.

• Lỗi sai: "a long time"
• Sửa: "for a long time"
• Giải thích: Cụm từ "for a long time" dùng để diễn tả khoảng thời gian.

8. The children were frightening by the thunder and lightning.

• Lỗi sai: "frightening"
• Sửa: "frightened"
• Giải thích: "frightening" là tính từ dùng để miêu tả, còn "frightened" là tính từ quá khứ phân từ dùng để chỉ trạng thái bị làm cho sợ hãi.

9. By the time she left the shop, she spent all of her money on clothes.

• Lỗi sai: "spent"
• Sửa: "had spent"
• Giải thích: Hành động "spend" xảy ra trước hành động "left" nên dùng thì quá khứ hoàn thành.

10. The country has significant changed since we came here in 2007.

• Lỗi sai: "changed"
• Sửa: "changed significantly"
• Giải thích: "significantly" là trạng từ bổ nghĩa cho động từ "changed".

11. My sister had worked in the bank for five years before she had been sent to Da Nang.

• Lỗi sai: "had been sent"
• Sửa: "was sent"
• Giải thích: Hành động "worked" xảy ra trước hành động "was sent" nên dùng quá khứ hoàn thành, nhưng hành động "was sent" không cần dùng quá khứ hoàn thành vì nó đã diễn tả một sự việc đã xảy ra trong quá khứ.