Conditionals

Zero conditional
When we talk about things that are generally or always true, we can use:
If/When/Unless plus a present form PLUS present simple or imperative
* If he gets there before me, ask himto wait.
* When you fly budget airline, you have to pay for your drinks and snacks.
* Unless you need more space, a small car is big enough for one person.
Note that we are not talking about aspecific event but something which is generally true.
In the condition clause, we can use a variety of present forms. In the result clause, there can only be the present simple or imperative.
* Ifyou visit London, go on the London Eye.
* If unemployment is rising, people tend to stay in their present jobs.
* If you've done that, go and have a coffee.
* When you go on holiday, takeplenty of sun cream. It'll be very hot.
* When I'm concentrating, please don't make so much noise.
* When I've finished an article, I always ask Kate to read it through.
Notice that 'unless' meansthe same as 'if not'.
* Unless he asks you politely, refuse to do any more work on the project.
* Unless prices are rising, it's not a good investment.
* Unless you've been there yourself,you don't really understand how fantastic it is.

The first conditional
We use the First Conditional to talk about future events that are likely to happen.
* If we take John, he'll be reallypleased.
* If you give me some money, I'll pay you back tomorrow.
* If they tell us they want it, we'll have to give it to them.
* If Mary comes, she'll want to drive.
The 'if' clause can be usedwith different present forms.
* If I go to New York again, I'll buy you a souvenir from the Empire State Building.
* If he's feeling better, he'll come.
* If she hasn't heard the bad news yet,I'll tell her.
The "future clause" can contain 'going to' or the future perfect as well as 'will'.
* If I see him, I'm going to tell him exactly how angry I am.
* If we don't get the contract,...