19. Were she not often absent from class, she could keep pace with her classmates.

20. Had you done as I advised you, you wouldn't have failed.

21. Should you be careful, you won't make a wrong decision.

22. Had you believed in his talent, he wouldn't have decided to leave.

Đảo ngữ của câu đk loại 1:

If+S+V, S+will/can/may/...+V

=>Should + S + V, S + will/can/may/ … +V

Đảo ngữ câu đk loại 2:

If+S+were+O, mệnh đề chính

=> Were+S+O, mệnh đề chính

If+S+Ved, mđề chính

=> Were+S+to V, mđề chính

Đảo ngữ câu đk loại 3: 

If+S+had+P2, mđc

=> Had+S+P2, mđc

Đảo ngữ câu đk trộn:

If+S+had+P2, S+would/could/might+V

=> Had+S+P2, S+would/could/might+V

Bài làm:

19. Were she not often absent from class, she could keep pace with her classmates.

→ Đảo ngữ câu điều kiện loại 2: Were + S1 + (not) + O, S2 + would/might/could… + V (infinitive)

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20. Had you done as I advised you, you wouldn't have failed.

→ Đảo ngữ câu điều kiện hỗn hợp: Had + S1 + (not) + past participle + O, S2 + would/might/could + V-infinitive

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21. Should you be careful, you won't make a wrong decision.

→ Đảo ngữ của câu điều kiện loại 1: Should + S1 + (not)+ V (hiện tại), S2 + will/may/might/should/can… + V (infinitive)

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22. Had you believed in his talent, he wouldn't have decided to leave.

→ Đảo ngữ câu điều kiện loại 3:  Had + S1 + (not) + past participle, S2 + would/might/could… + have + past participle

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@nam

xin hay nhất ạ!

chúc bạn học tốt nhó!