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.
The Second Conditional
The second conditional uses the past simple after if, then ‘would’ and the infinitive:
if + past simple, …would + infinitive
(We can use ‘were’ instead of ‘was’ with ‘I’ and ‘he/she/it’. This is mostly done in formal writing).
It has two uses.
First, we can use it to talk about things in the future that are probably not going to be true. Maybe I’m imagining some dream for example.
If I won the lottery, I would buy a big house.(I probably won’t win the lottery)
If I met the Queen of England, I would say hello.
She would travel all over the world if she were rich.
She would pass the exam if she ever studied.(She never studies, so this won’t happen)
Second, we can use it to talk about something in the present which is impossible, because it’s not true. Is that clear? Have a look at the examples:
If I had his number, I would call him. (I don’t have his number now, so it’s impossible for me to call him).
If I were you, I wouldn’t go out with that man.
How is this different from the first conditional?
This kind of conditional sentence is different from the first conditional because this is a lot more unlikely.
For example (second conditional): If I had enough money I would buy a house with twenty bedrooms and a swimming pool (I’m probably not going to have this much money, it’s just a dream, not very real)
But (first conditional): If I have enough money, I’ll buy some new shoes (It’s much more likely that’ll have enough money to buy some shoes)