Inglés sin barreras: advice

vendredi 15 août 2014

Top Tips Grammar: Obligation and necessity 2

Main points

* You use ‘need to’ to talk about necessity.
* You use ‘don’t have to’, ‘don’t need to’, ‘haven’t got to’, or ‘needn’t’ to say that it is not necessary to do something.
* You use ‘needn’t’ to give someone permission not to do something.
* You use ‘need not have’, ‘needn’t have’, ‘didn’t need to’, or ‘didn’t have to’ to say that it was not necessary to do something in the past.

a) You can use ‘need to’ to talk about the necessity of doing something.

- You might need to see a doctor.
- A number of questions need to be asked.

b) You use ‘don’t have to’ when there is no obligation or necessity to do something.

- Many women don’t have to work.
- You don’t have to learn any new typing skills.

You can also use ‘don’t need to’, ‘haven’t got to’, or ‘needn’t’ to say that there is no obligation or necessity to do something.

- You don’t need to buy anything.
- I haven’t got to go to work today.
- I can pick John up. You needn’t bother.

c) You also use ‘needn’t’ when you are giving someone permission not do something.

- You needn’t say anything if you don’t want to.
- You needn’t stay any longer tonight.

d) You use ‘need not have’ or ‘needn’t have’ and a past participle to say that someone did something which was not necessary. You are often implying that the person did not kno at the time that their action was not necessary.

- I needn’t have waited until the game began.
- Nell needn’t have worked.
- They needn’t have worried about Reagan.

e) You use ‘didn’t need to’ to say that something was not necessary, and that it was known at the time that the action was not necessary. You do not know if the action was done, unless you are given more information.

- They didn’t need to talk about it.
- I didn’t need to worry.

f) You also use ‘didn’t have to’ to say that it was not necessary to do something.

- He didn’t have to speak.
- Bill and I didn’t have to pay.

g) You cannot use ‘must’ to refer to the past, so when you want to say that it was important that something did not happen or was not done, you use other expressions.
You can say ‘it was important no to’, or use phrases like ‘had to make sure’ or ‘had to make certain’ in negative sentence.

- It was important not to take the game too seriously.
- It was necessary that no one was aware of being watched.
- You had to make sure that you didn’t spend too much.
- We had to do our best to make certain that it wasn’t out of date.

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Top Tips Abz Ingles: Part A - Part B
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See also:

Words related to Failure to Cooperate Irregular Verbs list

Common Phrasal Verbs Common Slangs

Common misspellings Regular vs Irregular Verbs

Common Errors Frequently confused words

Common Slangs Lista de Términos Gramaticales

Common Clichés Common Prepositions

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Top Tips Grammar: Mild obligation and advice

Main points

*You use ‘should’ and ‘ought’ to talk about mild obligation.
*You use ‘should have’ and ‘ought to have’ to say that there was a mild obligation to do something in the past, but it was not done.
*You can also use ‘had better’ to talk about mild obligation.

a) You can use ‘should’ and ‘ought’ to talk about a mild obligation to do something. When you use ‘should and ‘ought’, you are saying that the feeling of obligation is not as strong as when you use ‘must’.
‘Should’ and ‘ought’ are very common in spoken English. ‘Should’ is followed by the base form of a verb, but ‘ought’ is followed by a ‘to’- infinitive.
When you want to say that there is a mild obligation not to do something, you use ‘should not’, ‘shouldn’t’, ‘ought not’, or ‘oughtn’t’.

b) You use ‘should’ and ought’ in three main ways:
*when you are talking about was is a good thing to do, or the right thing to do.

- We should send her a postcard.
- We shouldn’t spend all the money.
- He ought to come more often.
- You ought not to see him again.

*When you are trying to advise someone about what to do or what not to do.

- You should claim your pension 3-4 months before you retire.
- You shouldn’t use a detergent.
- You ought to get a new TV.
- You oughtn’t to marry him.

*When you are giving or asking for an opinion about a situation. You often use ‘I think’, ‘I don’t think’, or ‘Do you think’ to start the sentence.

- I think that we should be paid more.
- I don’t think we ought to grumble.
- Do you think he ought not to go?
- What do you think we should do?

c) You use ‘should have’ or ‘ought to have’ and a past participle to say that there was a mild obligation to do something in the past, but that it was not done. For example, if you say ‘I should have given him the money yesterday’, you mean that you had a mild obligation to give him the money yesterday, but you did not give it to him.

- I should have finished my drink and gone home.
- You should have realised that he was joking.
- We ought to have stayed in tonight.
- They ought to have taken a taxi.

You use ‘should not have’ or ‘ought not to have’ and a past participle to say that it was important not to do something in the past, but that it was done. For example, if you say ‘I should not have left the door open’, you mean that it was important that you did not leave the door open, but you did leave it open.

- I should not have said that.
- You shouldn’t have given him the money.
- They ought not to have told him.
- She oughtn’t to have sold the ring.

d) You use ‘had better’ followed by a base form to indicate mild obligation to do something in a particular situation. You also use ‘had better’ when giving advice or when giving you opinion about something. The negative is ‘had better not’.

- I think I had better show this to you now.
- You’d better go tomorrow.
- I’d better not look at this.

Remember that the correct for is always ‘had better’ (not ‘have better’). You don’t use ‘had better’ to talk about mild obligation in the past, even though it looks like a past form.