Can & Could

Can & Can't

CAN = PERMISO

Utilizamos "can" para expresar habilidad, posibilidad, permiso y para pedir o solicitar algo.

Afirmativa: sujeto + can + forma base del verbo.

He can run very fast
The doctor can see you today
She can borrow my camera

Negativa: sujeto + can't or cannot + forma base del verbo.

I cannot/can't move my arm.

También utilizamos can't para expresar una certeza negativa cuando estamos seguros de que algo es imposible.

He can't be John's twin brother. They are so different!

Interrogativas: Can + sujeto + forma base del verbo.

Can you come here, please?

Respuestas cortas: pronombre + can o can't.

Can you breathe properly? Yes, I can / No, I can't

CAN'T = AUSENCIA DE PERMISO

[Students can't use their mobile phones in class]

Could

Utilizamos could para expresar habilidad y posibilidad en el pasado, para pedir permiso, para hacer peticiones formales o para hacer sugerencias o recomendaciones.

- You could watch films in English to improve your listening skills (sugerencia)

"Could" es el pasado de "can" y tiene la misma forma para todas las personas:

Afirmativa: sujeto + could + forma base del verbo (sin 'to')

I could play the piano when I was three years old.
We could stay out late.

Negativa: sujeto + could not / couldn't + forma base del verbo.

I couldn't go to school because I was ill

Interrogativa: Could + sujeto + forma base del verbo.

Could you tell me your phone number?

Respuestas cortas: subject pronoun + could or couldn't.

Could she read at the age of four? Yes, she could / No, she couldn't.

También utilizamos could para hacer deducciones en el presente (cuando pensamos que algo es posible).

He's got a rash (=sarpullido). It could be an allergic reaction.

RECUERDA: Could es el pasado de can y be able to es la forma verbal que complementa a can en los demás tiempos como el futuro

Be able to

Exercises

Can, could, be able to - ability and posibility