1. If water is heated to 100ºC, it boils.
CONDITIONAL CLAUSES
There are two clauses:
The condition clause with “if”
The result clause that states the possible outcome.
If water is heated to 100ºC, it boils.

2. If water is heated to 100ºC, it boils.
Zero
FACTS and TRUTHS
If + Pres. Simple, + Pres. Simple
If water is heated to 100ºC, it boils.
TO GIVE ORDERS
If + Pres. Simple, + Imperative
If Sam asks you for my telephone number, don’t give it to him.

3. If you come to my house, you will meet my parents.
FIRST - I
Possible situations in the FUTURE
If + Pres. Simple, + WILL infinitive
If you come to my house, you will meet my parents.
It can also be used to make THREATS and PROMISES
If you do that again, I will tell mum and dad.
I won’t use your mobile phone again if you don’t want me to.

4. SECOND - II If + Past Simple, + would infinitive
Imaginary or improbable situations in the present or future:
If + Past Simple, + would infinitive
If we had a week off, we would go to London.
If I were rich, I’d buy a new house.
It can also be used to give ADVICE
If I were you, I’d go to the doctor’s.

5. If they had come to the party, they would have had a great time.
THIRD - III
Impossible situations in the past
If + Past Perfect + would have participle
If they had come to the party, they would have had a great time.
It can also be used to talk about situations we REGRET
If I had studied harder, I wouldn’t have failed the exam.

6. CONDITIONAL CLAUSES I II III Zero If + Pres. Simple, + Pres. Simple
FACTS and TRUTHS
Zero
If + Pres. Simple, + Imperative
TO GIVE ORDERS
Possible situations in the FUTURE – THREATS - PROMISES I
If + Pres. Simple, + WILL infinitive
Imaginary situations in the present or future & ADVICE II
If + Past Simple, + would infinitive
III
Impossible situations in the past & REGRET
If + Past Perfect + would have participle