1. Lan said that she had bought that book at the bookstore the day before.

2. Nam said that he hadn't done his homework yet.

3. The teacher asked Lan if she was a new student.

4. Johnny said to his father that he didn't know how to do that exercise.

5. He said that he was meeting them at 4 o'clock the day before.

6. She said that her parents were arriving the next week.

Giải thích:

+ Hình ảnh.

+ Câu tường thuật đối với Yes/No questions: S + V-ed + if/whether + S + be/V lùi thì.

+ Câu tường thuật đối với H-Wh questions: S + V-ed + H/wh + S + be/V lùi thì.

`1`/ Lan said that she had bought this book at the bookstore ( I `->` She bởi vì cô ấy đang nói lại những gì cô ấy đã làm, lùi lại `1` thì past simple `->` past perfect  )

`2`/ Nam said that he hadn't done his homework yet ( lùi lại `1` thì present perfect `->` past perfect )

`3`/ Teacher asked Lan if she is a new student or not ( yes / not question thì dùng công thức if + S + to be + O + or not )

`4`/ Jonny said to his father not to know how to do this exercise ( do / does ( not ) dạng câu : not to + v infinite + O )

`5`/ He said he was meeting them at 4o'clock yesterday ( present continuous `->` past continuous )

`6`/ She said her parents were ariving next week ( present continuous `->` past continuous )

Reported speech là nói lại những gì đã làm, công thức thì chỉ cần lùi lại `1` thì,

Direct speech `->` reported speech:

Present simple `->` past simple

Present continuous `->` past continuous

Past simple/present perfect `->` past perfect

Past continuous `->` Past perfect continuous ( S +  had + been + v ing )

Past perfect `=` Past perfect