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1. Fred wouldn't do that unless he had your permission.
2. I won't bother to call you unless I hear from Mr. Brown.
3. Unless you agreed with him, Charles wouldn't even suggest it.
4. We can't write to Mr. Anderson unless he sends us his address.
5. The lawyer wouldn't say that unless he had strong evidence.
6. Unless you study harder, you're going to fail the examination.
7. I won't say anything unless Tom brings up the matter himself.
8. Unless more guests come, there will be enough food for everyone.
9. I wouldn't have believed it unless I had seen it with my own eyes.
10. Our dog wouldn't have barked unless he had heard a strange noise.
Câu đk loại 1 : If S Vs/es, S will V
Câu đk loại 2 : If S V2/ed, S would V
Câu đk loại 3 : If S had V3/ed, S would have V3/ed
Unless ~ if not