6. val asked me if scientists found life on Mars years ago

7. many people wondered if aliens or UFOs are real

8. sally asked hẻ best friend if they could go to the National Museum the day àter

`6`. Val asked me if scientists had found life on Mars many years before.

- Câu tường thuật với Yes/No-questions:

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

- Quá khứ đơn -> Quá khứ hoàn thành (find - found - found: tìm thấy)

- ago -> before

`7`. Many people wondered if aliens or UFOs were real.

- Hiện tại đơn -> Quá khứ đơn

`8`. Sally asked her best friend if they could go to the National Museum the next day.

- We -> they

- can -> could

- tomorrow -> the next day/ the following day