$\text{8. When did they return to America?}$

$\text{- two weeks ago -> chỉ thời gian -> Dùng when}$

$\text{- Returned -> QKD}$

$\text{9. What did Mrs Robinson buy?}$

$\text{- a poster -> chỉ đồ vật -> Dùng what}$

$\text{- Bought -> QKD}$

$\text{10. Where was your father last month?}$

$\text{- in Ha Noi -> chỉ nơi chốn -> Dùng where}$

$\text{- was -> QKD}$

`8.` When did they return to America?

`=>` thì quá khứ đơn

`=>` Dấu hiệu: two weeks ago

`=>` Mà two weeks ago chỉ thời gian nên dùng `->` when

`=>` when + did + S + V + ... ?

`9.` What did Mrs Robinson buy?

`=>` thì quá khứ đơn

`=>` Dấu hiệu: bought

`=>` Mà a poster chỉ đồ vật nên dùng `->` what

`=>` what + did + S + V + ... ?

`10.` Where was your father last month?

`=>` thì quá khứ đơn

`=>` Dấu hiệu: was

`=>` Mà in Ha Noi chỉ nơi chốn nên dùng `->` where

`=>` where + was + S + V + ... ?