Đáp án:

17. Lan said she was studying English then.

27. Nam said he had studied English for 3 years.

37. Mai said she and her friends bought those pens in that shop.

47. Lan said she would sell that bike the next week.

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Giải thích:

- Câu gián tiếp dạng tường thuật:

S1+ said/ told...+ (that)+ S2+ V(lùi thì)...

- Trong bài:

+ now-> then

+ this-> that, these-> those

+ next week-> the next week/ the following week

1. Lan said that she was studying English then

Câu gián tiếp tường thuật: S + said/told sb + (that) + S + V (lùi thì) 

Lùi thì: Hiện tại tiếp diễn `->` Quá khứu tiếp diễn

Đổi trạng từ: now `->` then

2. Nam said that he had studied English for 3 years

Câu gián tiếp tường thuật: S + said/told sb + (that) + S + V (lùi thì) 

Lùi thì: Hiện tại hoàn thành `->` Quá khứ hoàn thành

3. Mai said that she and her friends bought those pens in that shop

Câu gián tiếp tường thuật: S + said/told sb + (that) + S + V (lùi thì) 

Lùi thì: Hiện tại `->` Quá khứ

Đổi trạng từ: these `->` those; this `->` that

4. Lan said that she would sell that bike the following week

Câu gián tiếp tường thuật: S + said/told sb + (that) + S + V (lùi thì) 

Lùi thì: will + V `->` would + V

Đổi trạng từ: next week `->` the following week