Conditional clauses state the condition which must be satisfied before the main clause may be true. There are four main types:

Zero conditional
If + present tense / present tense
Not a true conditional, as the events described both happen.
If I go shopping alone, I spend too much money.

First conditional
If + present tense / future tense with will
Used to talk about something that will probably happen in the future, if something else happens.
If I have enough money, I’ll study abroad.
I’ll go to the party on my own if you don’t make a decision soon.

Second conditional
If + past tense / would, could, might
Used to talk about unlikely or impossible situations. Were instead of was is often used after if. This is common in both formal and informal styles. Some people consider were is more correct, especially in American English.
If I inherited some money, I’d go on an expensive holiday.
I wouldn’t watch TV if there was/were something better to do.

Third conditional
If + past perfect / would have, could have, might have + past participle
Used to speculate about what could have happened in the past.
If we had had a choice, we wouldn’t have left school at 16.
If Marisa had caught the right train, she wouldn’t have been late for class.

Other words with the same meaning as if.
- Unless has a similar meaning to if not, in the sense of except if.
I never wear a suit unless it is absolutely necessary.

- As/so long as, providing (that), provided (that), on condition that are all used to make conditions.
They were given permission to build the office block as long as they provided adequate parking facilities.


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