Could,should,must,ought To

[COOKIE72]

Hi

I was wondering if anyone could give me a brief explanation as to when and why we use these words?

Thanks to those of you who help

COOKIE72

[buggles]

"Should" and "ought to" are pretty much the same. You can use either to describe something you feel obliged to do. e.g. I should (ought to) go to visit my mother as it's her birthday.

"Must" is used for something you have to do. e.g. I must breathe to keep on living.

"Could" is used for something you are able to do. e.g. I could buy Mum a present if I had some money.

Hope this helps.

[COOKIE72]

thanks for your help Buggles.

[Clare James]

There's not just one simple answer, unfortunately. But here's a potted summary:

Could

(1) Used for polite requests in the present - 'Could I have a cup of tea?'
(2) Used to talk about ability in the past- 'When I was five I could ride a bike.'
(3) Used to talk about possible situations in the present you are making a guess about - 'This photo could be in France, but I'm not sure.'
(4) + have - Used to talk about possible situations in the past. 'The murderer could have left by the window.'

Should

(1) Used to give advice about the present - 'You should go to bed - you look tired.'
(2) + have - Used to criticise an action in the past - 'I shouldn't have said that.'

Must

(1) Used for strong obligation, usually by an authority figure. (Unlike 'have to') - "You mustn't touch this button, or the machine will stop.'
(2) Used to make strong suggestions in spoken English - 'You must come and visit sometime.'
(3) Used to talk about deductions or guesses you are fairly sure are true- 'The ground is wet, it must have rained.'

Ought to

(1) Used to give advice or recommendations about the present- 'You ought to be careful.'
(2) Used to criticise past actions 'I ought to have posted this letter yesterday, but I forgot.'

Hope this is some use to you.