(+) S + would/could/might + have + P2 + O + if + S + had + P2 + O

Vd:       I could have enjoyed that party If i had come back earlier.

Dịch:   Tôi đã có thể tham dự bữa tiệc đó nếu như tôi quay về sớm hơn.

( - )S + wouldn't/couldn't/might not + have + P2 + O + If + S + hadn't + P2 + O

Vd:       She wouldn't have had Visa to go back to her country If she hadn't found it.

Dịch:    Cô ấy sẽ không có Visa để về nước nếu cô ấy không tìm thấy nó.

( ? )Would/could/might + S+ have + P2 + O + If + S + had/hadn't + P2 + O

Vd:       Might their team have established the construction succesful If they had worked-hard and been patient?

Dịch:    Có thể nhóm của họ đã xây dựng công trình thành công nếu họ đã làm việc chăm chỉ và kiên nhẫn?

              Chúc bạn học tốt~~

(+)I would have called him if I had known his telephone.

(-)I wouldn't have taken the job if I had known the low salary.

(?)Would you have visited me if you had known I was in the hospital?