1. Structure
   1. IF/ condition / result
   2. result / IF/ condition
   3. we use shall, can, or may instead of will
2. First Conditional
   1. there is a real possibility that the condition will happen (FUTURE)
      1. IF / present simple / WILL + base verb
         1. If it rains I will stay at home.
         2. If Tara is free tomorrow he will invite her.
         3. If they do not pass their exam their teacher will be sad.
         4. If it rains tomorrow will you stay at home?
         5. If it rains tomorrow what will you do?
      2. WILL + base verb/ IF/ present simple
         1. I will tell Mary if I see her.
         2. He will invite Tara if she is free tomorrow.
         3. Their teacher will be sad if they do not pass their exam.
         4. Will you stay at home if it rains tomorrow?
         5. What will you do if it rains tomorrow?
      3. we use should, could or might instead of would
3. Second Conditional
   1. there is an unreal possibility that the condition will happen (FUTURE)
      1. IF / past simple / WOULD + base verb
         1. If I married Mary I would be happy.
         2. If Ram became rich she would marry him.
         3. If it snowed next July would you be surprised?
         4. If it snowed next July what would you do?
      2. WOULD + base verb / IF / past simple
         1. I would be happy if I married Mary.
         2. She would marry Ram if he became rich.
         3. Would you be surprised if it snowed next July?
         4. What would you do if it snowed next July?
      3. we use should, could or might instead of would
4. Third Conditional
   1. both the condition and result are impossible now
      1. IF / past perfect / WOULD HAVE + past participle
         1. If I had seen Mary I would have told her.
         2. If Tara had been free yesterday I would have invited her.
         3. If they had not passed their exam their teacher would have been sad.
         4. If it had rained yesterday would you have stayed at home?
         5. If it had rained yesterday what would you have done?
      2. WOULD HAVE + past participle / IF / past perfect
         1. I would have told Mary if I had seen her.
         2. I would have invited Tara if she had been free yesterday.
         3. Their teacher would have been sad if they had not passed their exam.
         4. Would you have stayed at home if it had rained yesterday?
         5. What would you have done if it had rained yesterday?
      3. we use should have, could have, might have instead of would have
5. Zero Conditional
   1. the condition always has the same result
      1. IF / present simple / present simple
         1. If I miss the 8 o'clock bus I am late for work.
         2. If I am late for work my boss gets angry.
         3. If people don't eat they get hungry.
         4. If you heat ice does it melt?
      2. present simple / IF /present simple
         1. I am late for work if I miss the 8 o'clock bus.
         2. My boss gets angry if I am late for work.
         3. People get hungry if they don't eat.
         4. Does ice melt if you heat it?