`color{red}{#Atr}`

`13.` Her boyfriend asked Lan if she had been at her house the night before

`-` Lùi thì: QKĐ `->` QKHT

`-` Đổi ngôi

`+` you `->` she

`+` your house `->` her house

`-` Đổi trạng ngữ chỉ thời gian: last night `->` the night before / the previous night

`-` Gián tiếp câu hỏi (Yes-No questions):

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

Đáp án : Her boyfriend asked Lan if she had been at her house the previous night

`-------------`

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

`-` Lùi thì :

`+`Quá khứ đơn `to` quá khứ hoàn thành

`+` Last night `to` the previous night

`+` You `to` she

`+` Your `to` her