Modals / Modal Perfects

En Bachillerato 1 ya aprendisteis este aspecto gramatical; haced clic en el siguiente enlace para repasarlo:

Trends Bachillerato 1 - Unit 4 - Grammar

MODAL VERBS:

· can (ability, request, possibility): --------------> can / be able to

I can play the piano.

Can you help me please?

My boss didn't come today, I can leave earlier.

· be able to (ability, possibility): se suele usar sobre todo para expresar el futuro de "can". -----------------------> be able to / can

I am able to play the piano.

I will be able to arrive on time. (future tense)

· can't (strong disbelief)

Who has arrived? It can't be John, he is still at work.

· could (ability): --------------------------------> could / be able to

I could play the piano when I was ten, now I don't remember anything.

I was able to play the piano when I was ten, now I don't remember anything.

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· should (advice): --------------------------------> should / ought to

You should see the new James Bond movie. It's great!

John should get a haircut.

What should I wear?

· ought to (advice): is more formal than "should". --------------------------------> ought to / should

Tom ought to be more careful.

You ought to eat more vegetables.

· might (possibility): ------------------------------> might / may / could

This might be the most difficult decision she would ever make.

I might lose my job.

She might call you tomorrow.

It might not rain tonight.

Might I give you a piece of advice? / Might we speak to you for a moment? (Only with "I" and "we" for the interrogative.)

· may (polite request, permission)

May I open the door?

· must (obligation): (must: es un tipo de obligación que suele venir impuesta de algún modo del exterior o por terceras personas. Aunque tiene una pequeña diferencia con "have to", en muchas ocasiones se usan de forma indistinta.) ---------------------------------> must / have to

I must study for tomorrow's test.

You must stay here until I come back.

We must be at the airport at three o'clock.

· must (strong belief):

He must be over 85 years old.

My keys must be around here somewhere.

Everyone is wearing a jacket. It must be cold.

He was running for three hours. He must be tired. (Although it seems obvious, it is not a fact that the runner is tired.)

· have to (obligation / necessity): (have to: es un tipo de obligación que se suele imponer uno a si mismo por voluntad propia. Aunque tiene una pequeña diferencia con "must", en muchas ocasiones se usan de forma indistinta.) -------------------------> have to / must / need to

I have to buy a new jacket because mine is very old.

John, I have to tell you the truth.

· mustn't (not allowed to or prohibition):

I mustn't play football. (=I'm not allowed to play football.)

· need to (necessity / obligation): --------------------------------> need to / have to

You need to go home and have some rest.

· needn't / don't need to / don't have to (lack of obligation or lack of necessity):

I needn't play football. / I don't need to play football. / I don't have to play football.

Extended information:

· don't need to / no need to (lack of obligation): we can use

both expressions to give permission to someone not to do something in the

immediate future.

You don't need to water the garden this evening.

It's going to rain tonight. (=no hace falta que riegues)

There's no need to water the garden this evening. It's going to rain tonight. (=no hace falta que riegues)

You don't need to shout. It's a good line. I can hear you perfectly. (=no hace falta que grites)

There's no need to shout. It's a good line. I can hear you perfectly. (=no hace falta que grites)

· don't have to / needn't (lack of obligation):

I don't have to work on

Sundays. (= no es

necesario que / no tengo que)

I needn’t work on Sundays. (= no es necesario que)

You don't have to eat

anything you don't like. (=

no es necesario que / no tengo que)

You need’t eat anything you don't like. (= no es necesario que)

· needn't have (+ -ed) (lack of obligation): When we say that someone needn't have done something, it means that they did it, but it was not necessary (es decir, se hizo algo que se podía no haber hecho

You needn't have washed the dishes. I

would've put them in the dishwasher. (=no hacía falta que labaras)

You needn't have watered the garden this evening. It's going to rain tonight. (=no hacía falta que regaras)

I needn't have prepared all that food. They phoned to say they wouldn't be coming. (=no hacía falta haber preparado)

· didn't need to (lack of obligation): We use didn't need to to say that something was not necessary under circumstances where it was not done; es decir, se evitó hacer algo que no era necesario hacer. (It is also sometimes used as "needn't have"):

The sun came out so we didn't need

to take any rainwear on the trip. (= no tuvimos que / no hizo

falta)

We had plenty of petrol in the

tank so I didn't

need to fill up. (= no tuvimos que / no hizo falta)

We didn't need to wait for long for them. They

arrived just after us. (= no tuvimos que / no hizo falta)

You didn't need to wash the dishes. I would've

put them in the dishwasher. / You needn't have washed the

dishes. I would've put them in the dishwasher.

I didn't need to prepare all that food. They phoned to say they wouldn't be coming. / I needn't have prepared all that food. They phoned to say they wouldn't be coming.

http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv317.shtml