Sử dụng "Unless" như thế nào

Unless (trừ khi) đồng nghĩa với if...not. Như if, unless được theo sau bởi một thì hiện tại, một thì quá khứ, hoặc một quá khứ hoàn thành (không bao giờ bởi một điều kiện). Unless được dùng thay vì if...not trong câu điều kiện dưới mọi kiểu. Thứ tự của mệnh đề không quan trọng với câu sử dụng unless.

Kiểu điều kiện 1 : Unless + thì hiện tại
Với If Tương đương với Unless
You will be sick if you don't stop eating. You'll be sick unless you stop eating.
I won't pay if you don't provide the goods immediately. I won't pay unless you provide the goods immediately.
If you don't study dilligently, you'll never understand trigonometry. Unless you study dilligently, you'll never understand trigonometry.
Kiểu điều kiện 2: Unless + thì quá khứ
Với If Tương đương với Unless
If he wasn't very ill, he would be at work. Unless he was very ill, he would be at work.
I wouldn't eat that food if I wasn't really hungry. I wouldn't eat that food unless I was really hungry.
She would be here by now if she wasn't stuck in traffic. She would be here by now unless she was stuck in traffic.
Kiểu điều kiện 3: Unless + quá khứ hoàn thành
Với If Tương đương với Unless
Our director would not have signed the contract if she hadn't had a lawyer present. Our director would not have signed the contract unless she had had a lawyer present.
I wouldn't have phoned him if you hadn't suggested it. I wouldn't have phoned him unless you'd suggested it.
They would have shot her if she hadn't given them the money. They would have shot her unless she'd given them the money.