`21`, He asked (me) if Daniel had sent the book to me.

- Câu tường thuật dạng Yes/No Questions : S + asked(O)/wondered/wanted to know + if/whether + S + V(lùi thì)

- Lùi thì : QKĐ -> QKHT 

- Đổi ngôi : you -> me 

`22,` Harry asked David to help him.

- Câu tường thuật dạng mệnh lệnh : S +  asked/told + sb + (not) + to V 

- Đổi ngôi : you -> him 

`23,` She asked not to tell her about it.

- Câu tường thuật dạng mệnh lệnh : S +  asked/told + sb + (not) + to V 

`24,` She asked me if I had bought the red dress.

- Câu tường thuật dạng Yes/No Questions : S + asked(O)/wondered/wanted to know + if/whether + S + V(lùi thì)

- Lùi thì : QKĐ -> QKHT 

- Đổi ngôi : you -> I

`25,` The boy asked who had made the noise.

- Câu tường thuật dạng Wh.questions: : S + asked(O)/wondered/wanted to know + W.H + S + V(lùi thì)

- Lùi thì : QKĐ -> QKHT 

21. He asked me if Daniel has sent the book to me ?

asked (+sb) + if/whether + S + V (lùi thì)

22. Harry asked him if he could help him.

asked (+sb) + if/whether + S + V (lùi thì) 

23. She told me not to tell her about it.

told + sb + not to + V-bare

24. She asked me whether I had bought the red dress.

asked (+sb) + if/whether + S + V (lùi thì) 

25. The boys asked Who had made the noise.

asked (+sb) + WH + S + V(lùi thì)