Although he was very tired, he tried to help me with my homework. -> Tired as But for your help, I couldn't have passed the exam. -> Had

1. Although he was very tired, he tried to help me with my homework.

-> Tired as he was, he tried to help me with my homework.

2. But for your help, I couldn't have passed the exam.

-> Had it not been for your help, I couldn't have passed the exam.

Hoặc: Had you not helped me, I couldn't have passed the exam.

Đảo ngữ câu điều kiện loại III: Had + S + (not) P2/Ved, S + Would have + P2/Ved