why
used in questions
You use why when you are asking a question about the reason for something.
‘I had to say no.’ – ‘Why?’
Why did you do it, Marta?
used when no answer is expected
You sometimes use why in questions without expecting an answer. For example, you can make a suggestion by asking a question beginning with Why don't.
Why don't we all go?
Why don't you write to her yourself?
You can emphasize that there is no reason for something to be done by asking a question beginning with Why should.
Why would he be angry with you?
‘Will you say sorry?’ – ‘No, why should I?’
You can emphasize that there is no reason why something should not be done by asking a question beginning with Why shouldn't.
Why shouldn't he go to college?
You can suggest that an action is pointless by using why followed by an infinitive without to.
Why tell the police? It won't do any good.
used in reported clauses
Why is often used in reported clauses.
He wondered why she had come.
You never really told me why you don't like him.
Why can be used on its own instead of a reported clause, if it is clear what you mean. For example, instead of saying ‘She doesn’t like him. I don't know why she doesn't like him', you can say ‘She doesn’t like him, I don't know why'.
They refuse to come – I don't know why.
He's certainly cheerful, though I can't think why.
used in relative clauses
Why is sometimes used in relative clauses with the word reason.
That is one reason why they were such a successful team.
➜ See reason