If + S + were .. , S + would / could + V1 (were áp dụng cho mọi chủ ngữ) 

→ EX: If I were you, I would learn English.

If + S + V2/ed , S + would / could + V1 

→ EX: If I had enough money, I would buy that house. 

→Câu điều kiện không có thật ở hiện tại

`Đảo` `ngữ:` 

Were + S+ O / to V,  S + would / could + V1 

→ EX: Were I you, I would quit my job.

→ EX: Were I to know him, I would invite him to my birthday party.