Summary of the three different types of conditional sentences in English.

1. On the way to Dublin
Conditional
sentences for 1st
Bachillerato
By Amadeus Serey Yáñez. Creative Commons.

2. On the way to Dublin
First conditional sentences
If I stay here
Structure:
If + present simple, will + infinitive
• If I stay here, I will see my friend.
• If it rains, I will stay at home.
• If you work hard, you will pass the exam.

3. On the way to Dublin
First conditional sentences
I’ll go unless you tell me to stay
If I study (CONDITION), I will pass my exams(RESULT).
I will pass my exams(RESULT) if I study(CONDITION).
I’ll go unless you tell me to stay.
=
I’ll go if you don’t tell me to stay.
(UNLESS= IF NOT)

4. On the way to Dublin
Second conditional sentences
If I had a million dollars
Structure:
If + past simple, would +
infinitive
• If we studied harder, we would pass our exams
more easily.
• If you asked Mike, he would come to the party.
• If I had a good job, I would be happier.

5. On the way to Dublin
Conditional Sentences type 3
The first conditional and second conditionals talk about the future. With the
third conditional we talk about the past, about a condition in the past that did
not happen. That is why there is no possibility for this condition:
CONDITION RESULT
Past Perfect WOULD HAVE + Past
Participle
If I had played tennis better I wouldn't have lost the
game.
Notice that we use the past perfect tense to talk about the impossible past
condition. We use WOULD HAVE + past participle to talk about the
impossible past result. The important thing about the third conditional is
Condition and result are impossible with the third conditional sentences.

6. On the way to Dublin
Conditionals with modal verbs
There are some special conditional forms for modal verbs in English:
would have + can = could have:
Jarim could have passed the exam if he had studied harder.
would have + shall = should have:
You should have passed the exam if you had studied harder.
would have + may = might have:
You might have passed the exam if you hadn't made so many mistakes.