Modal verbs

Can, could

"Can" funciona como verbo auxiliar modal y, por tanto, cumple las siguientes características:

- Va seguido de un verbo en infinitivo sin "to", excepto be able to, need to, have to y ought to.

- La tercera persona del singular no lleva -s en el presente simple.

- No necesita añadir el auxiliar do/does para la forma interrogativa y negativa.

- No tiene tiempos compuestos ni progresivos.

- No tiene infinitivo.

  Afirmativa e
interrogativa
Negativa Negativa
corta
Presente can cannot can't
Pasado could could not couldn't

Can

Afirmativo Negativo Interrogativo
I can do I cannot do I can't do Can I do?
You can do You cannot do You can't do Can you do?
He can do He cannot do He can't do Can he do?
She can do She cannot do She can't do Can she do?
It can do It cannot do It can't do Can it do?
We can do We cannot do We can't do Can we do?
You can do You cannot do You can't do Can you do?
They can do They cannot do They can't do Can they do?

Could

Afirmativo Negativo Interrogativo
I could do I could not do I couldn't do Could I do?
You could do You could not do You couldn't do Could you do?
He could do He could not do He couldn't do Could he do?
She could do She could not do She couldn't do Could she do?
It could do It could not do It couldn't do Could it do?
We could do We could not do We couldn't do Could we do?
You could do You could not do You couldn't do Could you do?
They could do They could not do They couldn't do Could they do?

"Can" sólo tiene dos formas: el presente y el pasado simple. Para otros tiempos verbales utilizaremos "to be able to" (ser capaz).

Ejemplos

I'll be able to go to the beach (futuro).

Podré ir a la playa.

They have been able to find a parking place (present perfect).

Han podido encontrar un lugar para aparcar.

Usos frecuentes de "can, could"

 1  Habilidad

'Can' se utiliza para expresar la capacidad (poder) o habilidad (saber) de alguien para hacer algo.

She can play the guitar Ella sabe tocar la guitarra
We couldn't speak French No sabíamos hablar francés

'Can' suele acompañar a los verbos de percepción o verbos de los sentidos como hear, feel, see, smell, taste.

She can hear it, but she can't find it Lo oye pero no puede encontrarlo
I can't see them No los veo

 2  Permiso o prohibición

En oraciones interrogativas se utiliza para pedir permiso; mientras que en oraciones negativas implica la prohibición de hacer algo.

You can't smoke in the malls No puedes fumar en los centros comerciales
Could I borrow your car? ¿Podría prestarme tu coche?

"Can" es una forma coloquial de pedir permiso. En el lenguaje formal se utiliza "may".

 3  Peticiones

Para pedir algo a alguien.

Can you do me a favour? ¿Puedes hacerme un favor?
Could you open the window? ¿Podrías abrir la ventana?

 4  Posibilidad

Para expresar que algo puede suceder.

It can be dangerous Puede ser peligroso
It could snow this weekend Podría nevar este fin de semana

17.3. Ejercicios I- Futuro simple, 'be going to' y presente simple

A) Elige la opción correcta.

1 I give you a lesson this evening.

I can give you a lesson this evening.

2 Do you think one day people to travel to the stars?

Do you think one day people will be able travel to the stars?

3 I do the shopping this week.

I can do the shopping this week.

4 We were very busy last week but we do all we had to.

We were very busy last week but we could do all we had to.

5 You get a better job if you'd work harder.

You could get a better job if you'd work harder.

6 He find his ticket for the concert.

He couldn't find his ticket for the concert.

7 hear what I was saying?

Couldn't you hear what I was saying?

8 She walk until she was three.

She wasn't able to walk until she was three.

9 you park in this street at weekends?

Can you park in this street at weekends?

10 play the guitar yet?

Can't you play the guitar yet?