`48,` My friend asked me if I was going to leave the following day.

`-` Reported speech: Yes - No question.

`-` Cấu trúc: S + asked + O + if/whether + S + V(lùi thì.)

`-` Đổi ngôi: you `->` I

`-` Lùi thì động từ: tobe going to + Vinf `->` was/were going to + Vinf

`-` Trạng từ chỉ thời gian: tomorrow `->` the following day/ the next day.

`49,` I asked Bill what time he had gone to bed the night before.

`-` Reported speech: Wh-question.

`-` Cấu trúc: S + asked + O + Wh-words + S + V(lùi thì).

`-` Đổi ngôi: you `->` he

`-` Lùi thì QKĐ `->` QKHT (had + Vpll)

`-` Trạng từ chỉ thời gian: last night `->` the night before/ the previous night. 

Đáp án:

`48,` My friend asked me if I was going to leave the following day.

- Câu tường thuật dạng NV (Yes/No-Question) `:`

`->` S + asked O / wondered / wanted to know + if / whether + S + V (lùi thì)

- Lùi thì: S + is / am / are + going to + V `->` S + was / were + going to + V

- Đổi ngôi: You `->` I

- Đổi thời gian: Tomorrow `->` The following day / the next day

`49,` I asked Bill what time he had gone to bed the previous night.

- Câu tường thuật dạng NV (Wh-Question) `:`

`->` S + asked O / wondered / wanted to know + Wh-Question + S + V (lùi thì)

- Lùi thì: Quá khứ đơn `->` Quá khứ hoàn thành 

- Đổi ngôi: You `->` He

- Đổi thời gian: Last night `->` The previous night / the night before