Conditionals describe situations and their results. There are four main types — and you must know which to use depending on whether the situation is real, possible, unreal, or imaginary in the past.
Zero conditional — general truths
Form: If + present simple, present simple. Used for facts that are always true.
- If you heat water, it boils.
- If it rains, the ground gets wet.
First conditional — real future possibility
Form: If + present simple, will + infinitive. Used for likely future events.
- If you take the medicine, you will not die.
- After he finds the treasure, will he sell it?
Tip — Note the question form: 'After he finds the treasure, will he sell it?' — present simple in the if-clause, will-question in the main clause.
Second conditional — unreal present
Form: If + past simple, would + infinitive. Used for unreal/hypothetical present situations.
- I'd buy a house too if I had enough money.
- If I were rich, I would travel the world.
Third conditional — imaginary past
Form: If + past perfect, would have + past participle. Used for impossible past situations.
- You wouldn't have died if only you had taken the medicine.
- We could have spent the whole weekend at the campsite if only we had brought enough food.
Tip — 'If only we had brought' = 'I wish we had brought' — both express regret about the past.
Alternatives: unless, as long as
'Unless' = 'if not'. 'As long as' = 'on condition that'.
- We won't go to the beach unless you learn swimming. (= if you don't learn)
- The project will be finished as long as you help me.
'or' meaning 'if not'
'You must learn swimming, or we will not go to the beach.' = 'We won't go to the beach unless you learn swimming.'