Unless ten years ago they had lived in the USA, they couldn't have been the citizens

`=>` If ten years ago they hadn't lived in the USA, they couldn't have been the citizens

`@` Kiến thức :

`-` Câu điều kiện loại `3` : If S + had P2 , S + would/could/might + have P2

`=>` Diễn tả sự việc không có thực , trái với quá khứ

`-` Unless `=` if not : nếu không

`-` Bổ sung "the" ; sửa "lives" `->` "lived"

Unless ten years ago they had lives in USA ,they couln't have been the citizens

⇒If ten years ago they hadn't lived in USA ,they couln't have been the citizens

Cấu trúc Unless=If not

Vês sau là they couln't have been the citizens không đụng tới vì giữ nguyên vế câu sau khi chuyển Unless thành If not

Cấu trúc câu điều kiện loại 3

If clause : If+S+had+V3

Main clause :S+would/could/might+have+V3