He can't go out because he has to study for his exam.

• If he didn't have to study for his exam, he could go out.

She is lazy so she can't pass the exam.

• If she weren't lazy, she could pass the exam.

He smokes too much; that's why he can't get rid of his cough.

• If he didn't smoke so much, he could get rid of his cough.

I can't play football this afternoon because I felt tired.

• If I hadn't felt tired, I could play football this afternoon.

Olga and Ivan weren't paying attention, so they didn't see the sign marking their exit from the highway.

• If Olga and Ivan had been paying attention, they would have seen the sign marking their exit from the highway.

She can't be employed because she doesn't have a college degree.

• If she had a college degree, she could be employed.

She walked to the meeting. She was late.

• If she hadn't walked to the meeting, she wouldn't have been late.

Unless you promise to return back, I won't lend you.

• If you don't promise to return back, I won't lend you.

We put off our trip because the weather was terrible.

• If the weather hadn't been terrible, we wouldn't have put off our trip.

Sally doesn't know what she has to do for homework because she was absent from school on Friday.

• If Sally hadn't been absent from school on Friday, she would know what she has to do for homework.

If you do not like this one, I'll bring you another.

• If you don't like this one, I'll bring you another.

Martin failed his driving test last week because he was very nervous.

• If Martin hadn't been so nervous, he wouldn't have failed his driving test last week.

But for the rain, we would have gone to the beach.

He will pay me tonight; I will have enough money to buy a car.

• If he pays me tonight, I will have enough money to buy a car.

Leave me alone or I'll call the police.

• If you don't leave me alone, I'll call the police.

If it rains tomorrow, we will cancel the picnic.

The car breaks down so often because you don't take good care of it.

• If you took better care of the car, it wouldn't break down so often.

Don't tell lies to your boss or you'll be fired at once.

• If you tell lies to your boss, you'll be fired at once.

He didn't revise all his lessons, so he failed the exam.

• If he had revised all his lessons, he wouldn't have failed the exam.

Rita is exhausted today because she didn't get any sleep last night.

• If Rita had gotten some sleep last night, she wouldn't be exhausted today