In English, there are many different ways of making sentences with if. It is important that:
1) You understand the difference between sentences that express real possibilities, and those that express unreal situations.
2) You learn which tenses follow each conditional
a) Zero Conditional
We use the zero conditional to express a situation that is always true.
Present simple + present simple
- If I read too much, I get a headache
b) First Conditional
We use the first conditional to express real possibilities.
Present simple + future
- If I go to the concert, I'll see Ricky Martin
c) Second Conditional
We use the second conditional to express an unreal situation. The situation or condition is improbable, impossible, imaginary or contrary to known facts.
Past simple + would (conditional)
- If I won the lottery I would buy a house
d) Third Conditional
We use the third conditional to imagine the consequence of events that happened or began to happen in the past.
Past Perfect + would have + past participle
- If I had known, I would have gone to visit you
e) Mixed Conditional (2nd & 3rd Conditional)
The mixed conditional is a mixture between the 2nd and 3rd conditional.
- If the weather had been better, we would go back next year
- If I'd been born in 1980, I'd be 23 years old now. (remember: I'd been born - I'd = I had; I'd be 23 years - I'd = I would)