I could sire you could sire he could sire we could sire you could sire they could sire
Forma con V-ing
I could be siring you could be siring he could be siring we could be siring you could be siring they could be siring
Perfecto
I could have sired you could have sired he could have sired we could have sired you could have sired they could have sired
Perfecto con V-ing
I could have been siring you could have been siring he could have been siring we could have been siring you could have been siring they could have been siring
Negación
Forma simple
I could not sire you could not sire he could not sire we could not sire you could not sire they could not sire
Forma con V-ing
I could not be siring you could not be siring he could not be siring we could not be siring you could not be siring they could not be siring
Perfecto
I could not have sired you could not have sired he could not have sired we could not have sired you could not have sired they could not have sired
Perfecto con V-ing
I could not have been siring you could not have been siring he could not have been siring we could not have been siring you could not have been siring they could not have been siring
Forma interrogativa
Forma simple
could I sire? could you sire? could he sire? could we sire? could you sire? could they sire?
Forma con V-ing
could I be siring? could you be siring? could he be siring? could we be siring? could you be siring? could they be siring?
Perfecto
could I have sired? could you have sired? could he have sired? could we have sired? could you have sired? could they have sired?
Perfecto con V-ing
could I have been siring? could you have been siring? could he have been siring? could we have been siring? could you have been siring? could they have been siring?
Forma interro-negativa
Forma simple
could I not sire? could you not sire? could he not sire? could we not sire? could you not sire? could they not sire?
Forma con V-ing
could I not be siring? could you not be siring? could he not be siring? could we not be siring? could you not be siring? could they not be siring?
Perfecto
could I not have sired? could you not have sired? could he not have sired? could we not have sired? could you not have sired? could they not have sired?
Perfecto con V-ing
could I not have been siring? could you not have been siring? could he not have been siring? could we not have been siring? could you not have been siring? could they not have been siring?