I could sit you could sit he could sit we could sit you could sit they could sit
Forma con V-ing
I could be sitting you could be sitting he could be sitting we could be sitting you could be sitting they could be sitting
Perfecto
I could have sat you could have sat he could have sat we could have sat you could have sat they could have sat
Perfecto con V-ing
I could have been sitting you could have been sitting he could have been sitting we could have been sitting you could have been sitting they could have been sitting
Negación
Forma simple
I could not sit you could not sit he could not sit we could not sit you could not sit they could not sit
Forma con V-ing
I could not be sitting you could not be sitting he could not be sitting we could not be sitting you could not be sitting they could not be sitting
Perfecto
I could not have sat you could not have sat he could not have sat we could not have sat you could not have sat they could not have sat
Perfecto con V-ing
I could not have been sitting you could not have been sitting he could not have been sitting we could not have been sitting you could not have been sitting they could not have been sitting
Forma interrogativa
Forma simple
could I sit? could you sit? could he sit? could we sit? could you sit? could they sit?
Forma con V-ing
could I be sitting? could you be sitting? could he be sitting? could we be sitting? could you be sitting? could they be sitting?
Perfecto
could I have sat? could you have sat? could he have sat? could we have sat? could you have sat? could they have sat?
Perfecto con V-ing
could I have been sitting? could you have been sitting? could he have been sitting? could we have been sitting? could you have been sitting? could they have been sitting?
Forma interro-negativa
Forma simple
could I not sit? could you not sit? could he not sit? could we not sit? could you not sit? could they not sit?
Forma con V-ing
could I not be sitting? could you not be sitting? could he not be sitting? could we not be sitting? could you not be sitting? could they not be sitting?
Perfecto
could I not have sat? could you not have sat? could he not have sat? could we not have sat? could you not have sat? could they not have sat?
Perfecto con V-ing
could I not have been sitting? could you not have been sitting? could he not have been sitting? could we not have been sitting? could you not have been sitting? could they not have been sitting?