In English we have four ways to make conditional (if) sentences. Here is how to make them…
0 Conditional – is used for scientific facts or general truths. ‘If’ can be substituted for ‘when’.
‘If you boil water to 100°C, it boils.’
‘When you boil water to 100°C, it boils.’
1st Conditional – is used with ‘will/can + base verb’ for a probable future result.
‘If you study hard, your English will improve.’
‘If I get enough sleep, I will feel better.’
2nd Conditional – uses the ‘simple past’ with ‘modal + base verb’ for imagined, impossible or unreal future situations.
‘If I won the lottery, I would buy a plane.’
‘If you met Johnny Depp, what would you ask him?’
3rd Conditional – uses the ‘past perfect’ with ‘modal + have + past participle’. It is usually used to express a past regret about something which did not happen in the past.
‘If I had won the lottery, I would have bought a plane.’
‘If I had been taller, I could have played in the NBA.’
More than above conditions, Mixed conditional also be used. Mixed Conditional is mixed between 2nd and 3rd Conditional.