Zero conditional

Zero conditionals мы употребляем, когда говорим о реальных событиях, привычках, научных фактах, о том, что всегда правда 

В zero conditional оба глагола употребляются в present simple:

If I get hiccups, I hold my breath or drink a cup of water.
If you freeze water, it turns into ice.
If you boil water, it evaporates.

First Conditional = вероятно/возможно

If + present simple, will + infinitive (future simple)

If I see a snake, I will scream (I travel across India, that's why it is possible)
If all the political parties work together, there won't be so many problems.


If you see a black cat, you'll have good luck.
If you break a mirror, you'll have seven years' bad luck.
If you walk under a ladder, you'll be unlucky.


If you cook dinner, I'll do the washing up.
If you do the washing, I'll do the ironing.
If you wash the car, I'll do the vacuuming.


If you watch too much television, you'll get square eyeballs.
If you don't do your homework, you won't pass your exams.

Second Conditional = невероятно/невозможно 

If + past simple, would + infinitive

If I saw a shake in my bed, I would scream (very unlikely situation)
If I won the lottery I would give up my job immediately. (I think it is unlikely).
If I were to win the lottery, I would buy myself a house.

were to + infinitive is used to make a statement sound even more unlikely
If I were a rich woman, I would travel the world.

Third Conditional and Inversion = сожаления о прошлом/альтернативы в прошлом

If + past perfect simple/continuous, would/might/could + have + past participle

If I had booked tickets earlier, I would have bought them cheaper.
If I had studied harder, I would have passed my exam.

Had I booked tickets earlier, I would have bought them cheaper. (inversion - more formal)