There are four types of conditional sentences. It’s important to understand the difference between them.
Zero conditional:
We use this structure to talk about things that are always true, for example, scientific facts. We want to emphasise that if a certain condition is true, a particular result will happen.
Let’s have a look at the example:
If the sun rises, life goes on.
When the water reaches 100 degrees, it boils.
Remember that you use present simple tense in zero conditional.
The probability of something happening is 100%
First conditional:
We use the First conditional to talk about a possible situation in the future. The probability of something happening is 50%.
For example,
If you study hard, you will pass your exams.
Remember that we use present simple in if-clause and future simple in the second part of the sentence.
Let´s compare two sentences:
If I go to Italy, I meet my friend Fiona.
If I go to Italy, I will meet my friend Fiona.
The first sentence tells us that you always meet Fiona every time you go to Italy. The second sentence means that if you go to Italy, you will probably meet Fiona (at least once).
Second conditional:
We use second conditional to talk about almost improbable or imaginary situations in the present or future.
The probability of something happening is 1-2%.
The correct way to form second conditional is to use the simple past tense in the if-clause and an auxiliary modal verb (e.g., could, should, would, might) in the main clause.
Let´s have a look at the example:
If I were a dolphin, I would be incredibly social and altruistic:)
If I were a millionaire, I would travel to the Moon.
Keep in mind that we use past simple in the if-clause and would plus infinitive in the main clause.
Third conditional:
We use third conditional to explain that the present situation would be completely different if we could change the past. The probability of something happening is 0%.
If I had studied harder, I would have got better job prospects.
I would have lived in France if I hadn´t moved my house,
Remember that we use past perfect in the if-clause and would+ have + the past participle in the main clause.
Keep in mind that we can mix second and third conditionals!
As for punctuation, we don´t put comma before “if”.
