1. If I had been working at the restaurant last night, I would have waited on your table.

⇔ 1. Had I been working at the restaurant last night, I would have waited on your table.

2. If they had been paying attention, they would have seen the sign marking their exit from the highway.

⇔ 2. Had they been paying attention, they would have seen the sign marking their exit from the highway.
3. Carol would have answered the phone if she hadnt been studying.

⇔ 3. Had Carol not been studying, she would have answered the phone.

4. If the sun hadnt been shining, we wouldnt have gone to the beach yesterday.

⇔ 4. Had the sun not been shining, we wouldn't have gone to the beach yesterday.

5. If the music hadnt been playing loudly at the restaurant, I would have heard everything Mr Lee said during dinner.

⇔ 5. Had the music not been playing loudly at the restaurant, I would have heard everything Mr Lee said during dinner.

`1.`  had I been working at the restaurant last night, I would have waited on your table

`2.` had they been paying attention, they would have seen the sign marking their exit from the highway
`3.` had Carol not been studying, she would have answered the phone

`4.`  had the sun not been shining, we wouldn't have gone to the beach yesterday

`5.` had the music not been playing loudly at the restaurant, I would have heard everything mr Lee said during dinner

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`-` Áp dụng:

`@` Cấu trúc đảo ngữ câu điều kiện loại `3:`

`->` Had + S1 + (not) + past participle, S2 + would/might/could… + have + past participle

`->` Đảo ngữ câu điều kiện loại này lại có phần công thức đơn giản nhất khi chúng ta chỉ việc đảo “Had” lên đầu câu và bỏ “If”. Cách đảo này giúp nhấn mạnh ý ở mệnh đề giả thiết hơn bình thường.