Tuesday, 26 November 2013

Speakout Advanced p 57. Modal Verbs . Extra Grammar

Modal Verbs of Obligation, Permission and Necessity

We can use have to + infinitivemust + infinitive and should + infinitive to express obligation (something you have to do).

have to /
don't have to
strong obligation (possibly from outside)
·         Children have to go to school.
no obligation

·         I don't have to work on Sundays.
You don't have to eat anything you don't like.
must / mustn't
strong obligation (possibly based on the speaker's opinion)
·         I must study today.
negative obligation

·         You mustn't smoke here.
should / shouldn't
mild obligation or advice
·         You should save some money.
mild negative obligation or advice
·         You shouldn't smoke so much.
Be careful about the difference between mustn't and don't have to!
Mustn't means it's not allowed, or it's a bad idea:
·         You mustn't eat so much chocolate, you'll be sick

Don't have to means you don't need to do something, but it's fine if you want to do it:
·         I don't have to get up early at the weekend (of course, if I want to get up early, that's fine, but I can stay in bed if I want).

had to / didn't have to
obligation in the past
·         I had to wear a school uniform when I was a child.
no obligation in the past
·         We didn't have to go to school on Saturdays.
changes to 'had to'
was not to
should have + pp / shouldn't have + pp
a past action which didn't happen: the advice / regret is too late
·         You should have gone to bed earlier, now you have missed the train.
a past action which didn't happen: the advice / regret is too late
·         You shouldn't have taken that job, it was a bad idea.

* Remember 'must have done' is a modal verb of deduction or speculation, not obligation in the past. For example: Julie must have left. Her coat's not here.

Was not to: must changes to had to and mustn't becomes was not to for obligation in reported speech. E.g. you mustn't tell my mother: she said I was not to tell her mother.
The most common modal verbs for talking about permission and obligation are can/ could, must and should/ ought to.
            I couldn’t take any photos in the museum, so I bought some postcards.
            Passengers on the bus mustn’t distract the driver.
            We should/ought to drive home on the motorway – it’s much quicker.
We can use should have or ought to have + past participle to talk about past events which did not happen and which we regret.
We should have / ought to have driven home on the motorway – it would have been quicker.
Had better is stronger and more urgent than should/ought to and is often used to give strong advice or a warning. It normally refers to the immediate future.
            You’d better post the parcels today or they won’t get there in time.
The negative is had better not NOT hadn’t better.
We also use have to express obligation. It can be used in any tense.
            All passengers will have to fill in a form before landing.
You don’t have to tip the waitress unless you think the service was especially good.
We can also use have got to to express obligation, but it is normally used for specific occasions rather than repeated or general obligation.
            I’ve got to buy a birthday present for my brother.
We use need/don’t need + to + infinitive to say something is necessary/ unnecessary. You can use these forms for habitual, general, and specific necessity.
            You usually need to check in at least two hours before a flight leaves.
            I don’t need to take a raincoat. It’s going to be hot today.
As a modal (NEED + infinitive without to), NEED tends to occur only in the negative and interrogative.
You need not wait.  
Need we wait?
My brother-in-law and his family stayed with us at Christmas. Need I say more?
When we want to say that something is unnecessary on a specific occasion, we can also use needn’t + infinitive without to.
            You needn’t lock the car. Nobody will steal in this village.
We use don’t need to (NOT needn’t) for habitual or general necessity.
I don’t need to wear glasses. My eyesight is still good (NOT I needn’t wear glasses)
A modal must be followed by a verb so we cannot use the modal verb pattern if followed by a noun: Do you need anything? 
When something was not necessary, but you did it, we can use either needn’t + have + past participle or sometimes didn’t need to + infinitive.
We needn’t have booked / didn’t need to book a table. The restaurant is empty!
When something was not necessary so you did not do it, we must use didn’t need to.
We had plenty of petrol so we didn’t need to stop, which saved time.        NOT We had plenty of petrol so we needn’t have stopped, which saved time.   
I didn't need to spend very long on my homework last night- it was quite easy.       
As a modal (DARE + infinitive without to), DARE tends to occur only in the negative and interrogative.  
 They daren't ask for any more money.  
I dare not go yet. 
Dare we go yet?

Alternatively, we can also use DARE as a full verb followed by the infinitive with or without to: 
 He didn't dare (to) say what he thought. 
I don't dare (to) go yet. 
Do we dare (to) go?

We often use be able to or be allowed to + infinitive to talk about what is possible or permitted instead of can, particularly when we want to use a form which can does not have.
From tomorrow we won’t be able to park here. 
You’re not allowed to smoke in the classroom.
Be permitted to + infinitive is used in formal situations, e.g. notices and announcements, to say what can / can’t be done according to the law or to rules and regulations.
It is not permitted to take mobiles into the exam room.                                
We do not use it followed by allowed to + inf. NOT It isn’t allowed to take mobiles into the exam room.
We can also use be supposed to + infinitive to say what people should or shouldn’t do, often because of rules. There is often a suggestion that the rules are not necessarily obeyed.
Students are not supposed to stay out after 12.00, but everyone does.    
We are supposed to check in at 3.50. What’s the time now?            
You aren’t supposed to park here - it’s a surgery entrance.
Be allowed to, be permissible to; be forbidden to, be banned from; be/feel compelled to, be compulsory; be forced to, be obligatory; have the courage to.
We weren’t allowed to contact the teachers. (It wasn’t permissible to contact them.)

permissible /pəˈmɪsəbl/ acceptable according to the law or a particular set of rules. E.g. permissible levels of nitrates /ˈnaɪtreɪt/ in water. Permissible (for somebody) (to do something) It is not permissible for employers to discriminate on grounds of age.
ban somebody from something E.g. He was banned from the meeting. 
ban somebody from doing something E.g. She's been banned from leaving Greece while the allegations are investigated. 

compel: /kəmˈpel/ to force somebody to do something; to make something necessary.  
Compel somebody to do something E.g. The law can compel fathers to make regular payments for their children. I feel compelled to write and tell you how much I enjoyed your book.
Compel something Last year ill health compelled his retirement.

 compulsory: /kəmˈpʌlsəri/ E.g. It is compulsory for all motorcyclists to wear helmets. English is a compulsory subject at this level. Compulsory education/ schooling. Compulsory redundancies

They were forced to wear army uniform. (Army uniform was compulsory) 

obligatory (for somebody) (to do something): /əˈblɪɡətri/ E.g. It is obligatory for all employees to wear protective clothing

courage: /ˈkʌrɪdʒ/
pluck up (the) courage (to do something): to make yourself do something even though you are afraid to do it. E.g. I finally plucked up the courage to ask her for a date. 

Click HERE for more information on DARE and NEED 

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