`1.` Mum wanted to know if Peter had done his homework yet. 

`-` Thì QKD `->` Thì QKHT `->` have done `->` had done (had + VpII)

`-` your `->` his (thay thế cho Peter) 

`2.` Mary asked Sue where she was going to spend her holiday that summer. 

`-` Sue = she (her)

`-` Thì TLD (am/is/are + going to + V-inf) `->` was/were + going to + V-inf (lùi thì)

`-` your `->` her (thay thế cho "she")

`-` this summer `->` that summer (đổi trạng từ chỉ thời gian) 

`3.` Tom asked me if I knew how long it was from London to Cambridge.

`-` Thì HTD `->` Thì QKD `-` know (V-inf) `->` knew (V-ed) `-` is `->` was (tobe)

`-` you `->` I (Tom hỏi tôi liệu tôi có biết...) 

`4.` Cindy asked Carol if she would phone her as soon as she arrived in Oxford.

`-` Cindy = Carol = she (Cô ấy) - her

`-` Cindy hỏi Carol liệu cô ấy sẽ gọi cho cô ngay khi cô ấy đến Oxford ko.

`-` Thì TLD (will phone) `->` would + V-inf (would phone) - lùi thì.

`-` Thì HTD (Arrive) `->` arrived (Thì QKD - V-ed) - lùi thì. 

`5.` Grandma was interested in knowing if the children had played football in the park the day before.

`-` Thì QKD `->` Thì QKHT `-` V-ed `->` had + VpII = had played - lùi thì

`-` yesterday `->` the day before/the previous day (đổi trạng từ chỉ thời gian)

`6.` Father wanted to know how much the ticket for the concert cost. 

`-` cost là động từ bất quy tắc, dạng V-ed và VpII của nó là "cost" (giữ nguyên).

`-` Thì HTD `->` Thì QKD `->` cost (HTD) `=>` cost (QKD) 

`-` Câu tường thuật dạng Yes or No questions:

`-` Cấu trúc: S + asked (sb)/wanted to know/... + if/whether + S + V lùi thì 

`-` Câu tường thuật dạng Wh-questions:

`-` Cấu trúc: S + asked (sb)/wanted to know/... + Wh-questions + S + V lùi thì 

1. Mum wanted to know if Peter had done his homework.

cấu trúc câu gián tiếp yes/no: S + asked/wanted to know + if/whether + S + V + ....

- Câu trực tiếp thì HTHT => cấu gián tiếp thì QKHT

2. Mary asked Sue where she was going to spend her holiday this summer.

Câu gián tiếp câu hỏi wh: S + asked/wanted to know + Wh + S + V + ....

- Câu trực tiếp thì TLG => câu gián tiếp dùng was/were going to V

3. Tom asked me if I knew how long it was from London to Cambridge.

- Cấu trúc như câu 1.

- câu trực tiếp HTĐ => câu gián tiếp QKĐ

4. Cindy asked Carol if he would phone her as soom as he arrived in Oxford.

- Cấu trúc câu gián tiếp dạng câu hỏi yes/no: giống câu 1

- Thì TLD => câu gián tiếp tương lai đơn trong QK (would + V)

5. Grandma was interested in knowing if the children had played football in the park the day before.

- Câu trúc câu gián tiếp dạng câu hỏi yes/no: như câu 1

- Thì QKĐ => thì QKHT trong câu gián tiếp

- Yesterday => the day before

6. She asked how much the ticket for the concert cost.

- thì HTĐ => QKĐ trong câu gián tiếp

- động từ cost là động từ bất quy tắc: cost - cost - cost. 

Mong bạn cho ctlhn. Thanks!