8.25 Conditional clauses

When you want to talk about a possible situation and its consequences, you use a conditional clause.

Conditional clauses are used:

* to talk about a situation which sometimes exists or existed

• If they lose weight during an illness, they soon regain it afterwards.
• Government cannot operate effectively unless it is free from such interference.
• If I saw him in the street, he'd just say 'Good morning.'

* to talk about a situation which you know does not exist

• If England had a hot climate, the attitude would be different.
• If I could afford it I would buy a boat.

* to talk about a situation when you do not know whether it exists or not

• If he is right it would be possible once more to manage the economy in the old way.
• There's no reason why she should have come here unless it was to cadge free drinks.

* to talk about a situation which may exist in the future.

• If I marry Celia we shall need the money to live on.
• If I went back on the train it'd be cheaper.
• Don't bring her unless she's sober.

Sentences containing conditional clauses are sometimes called conditional sentences.

8.26

Conditional clauses usually begin with 'if' or 'unless'.

You use 'if' to say that a consequence of something happening or being the case would be that something else would happen or be the case.

• If you do that I shall be very pleased.
• If I asked for something I got it.
• They will even clean your car if they're in the mood.

When an 'if'-clause is put first, 'then' is sometimes put at the beginning of the main clause.

• If this is what was happening in the Sixties, then I'm glad I wasn't around then.

'Unless' means 'if...not'. For example, 'You will fail your exams unless you work harder' means 'If you do not work harder, you will fail your exams'.

• There can be no new growth unless the ground is cleared.
• Nobody gets anything unless they ask for it.

Clauses beginning with 'unless' usually go after a main clause.