Conditionals are sentences with two clauses – an ‘if clause and a main clause – that are closely related. Conditional sentences are often divided into different types.
We use the zero conditional to talk about things that are always true.
- If you heat water, it boils.
- When the sun goes down, it gets dark.
- It lights up if you push that button.
The present simple is used in both clauses.
We use the first conditional when we talk about real and possible situations.
- I’ll go shopping on the way home if I have time.
- If it’s a nice day tomorrow, we’ll go to the beach.
- If Arsenal win, they’ll be top of the league.
In first conditional sentences, the structure is usually if + present simple and will + infinitive. It’s not important which clause comes first.
The second conditional is used to talk about ‘unreal’ or impossible things.
- If I won a lot of money, I’d buy a big house in the country.
- Where would you live if you could live anywhere in the world?
- If you didn’t smoke so much, you’d feel a lot better.
The structure is usually if + past simple and would + infinitive. It’s not important which clause comes first.
Look at the difference between the first and second conditionals.
- In January: If it snows tomorrow, I’ll go skiing. It might snow tomorrow.
- In August: If it snowed tomorrow, I’d go skiing. It almost certainly won’t snow tomorrow.
NOTE: Although many conditional sentences use if + will/would, conditional sentences can also use other words instead of ‘if’ – e.g. ‘when’ ‘as soon as’ ‘in case’ Other modal verbs can be used instead of ‘will/would’ – e.g. ‘can/could’, ‘may’ ‘might’.
Other types of conditional sentences are covered in another section.