I could swim you could swim he could swim we could swim you could swim they could swim
Forma con V-ing
I could be swimming you could be swimming he could be swimming we could be swimming you could be swimming they could be swimming
Perfecto
I could have swum you could have swum he could have swum we could have swum you could have swum they could have swum
Perfecto con V-ing
I could have been swimming you could have been swimming he could have been swimming we could have been swimming you could have been swimming they could have been swimming
Negación
Forma simple
I could not swim you could not swim he could not swim we could not swim you could not swim they could not swim
Forma con V-ing
I could not be swimming you could not be swimming he could not be swimming we could not be swimming you could not be swimming they could not be swimming
Perfecto
I could not have swum you could not have swum he could not have swum we could not have swum you could not have swum they could not have swum
Perfecto con V-ing
I could not have been swimming you could not have been swimming he could not have been swimming we could not have been swimming you could not have been swimming they could not have been swimming
Forma interrogativa
Forma simple
could I swim? could you swim? could he swim? could we swim? could you swim? could they swim?
Forma con V-ing
could I be swimming? could you be swimming? could he be swimming? could we be swimming? could you be swimming? could they be swimming?
Perfecto
could I have swum? could you have swum? could he have swum? could we have swum? could you have swum? could they have swum?
Perfecto con V-ing
could I have been swimming? could you have been swimming? could he have been swimming? could we have been swimming? could you have been swimming? could they have been swimming?
Forma interro-negativa
Forma simple
could I not swim? could you not swim? could he not swim? could we not swim? could you not swim? could they not swim?
Forma con V-ing
could I not be swimming? could you not be swimming? could he not be swimming? could we not be swimming? could you not be swimming? could they not be swimming?
Perfecto
could I not have swum? could you not have swum? could he not have swum? could we not have swum? could you not have swum? could they not have swum?
Perfecto con V-ing
could I not have been swimming? could you not have been swimming? could he not have been swimming? could we not have been swimming? could you not have been swimming? could they not have been swimming?