2. 1st Conditional If I study, I will pass the exam. I know I will pass. It is possible, because I just need to study! We use the first conditional to talk about a POSSIBLE situation, now or in the future. If + subject + present simple, subject + future
3. 2nd Conditional If I studied, I would pass the exam. I should be studying, but I’m playing instead. So passing the exam is improbable or imaginary. We use the 2nd conditional to talk about IMPROBABLE or IMAGINARY situations , now or in the future. If + subject + past simple, subject + would + infinitive
4. 3rd Conditional If I had studied, I would have passed the exam Now it’s too late. Bart failed the exam, because he didn’t study. We use the 3rd conditional to talk about a situation in the past that DIDN’T HAPPEN – always IMAGINARY If + subject + past perfect, subject + would have + past participle