I could alter you could alter he could alter we could alter you could alter they could alter
Forma con V-ing
I could be altering you could be altering he could be altering we could be altering you could be altering they could be altering
Perfecto
I could have altered you could have altered he could have altered we could have altered you could have altered they could have altered
Perfecto con V-ing
I could have been altering you could have been altering he could have been altering we could have been altering you could have been altering they could have been altering
Negación
Forma simple
I couldn't alter you couldn't alter he couldn't alter we couldn't alter you couldn't alter they couldn't alter
Forma con V-ing
I couldn't be altering you couldn't be altering he couldn't be altering we couldn't be altering you couldn't be altering they couldn't be altering
Perfecto
I couldn't have altered you couldn't have altered he couldn't have altered we couldn't have altered you couldn't have altered they couldn't have altered
Perfecto con V-ing
I couldn't have been altering you couldn't have been altering he couldn't have been altering we couldn't have been altering you couldn't have been altering they couldn't have been altering
Forma interrogativa
Forma simple
could I alter? could you alter? could he alter? could we alter? could you alter? could they alter?
Forma con V-ing
could I be altering? could you be altering? could he be altering? could we be altering? could you be altering? could they be altering?
Perfecto
could I have altered? could you have altered? could he have altered? could we have altered? could you have altered? could they have altered?
Perfecto con V-ing
could I have been altering? could you have been altering? could he have been altering? could we have been altering? could you have been altering? could they have been altering?
Forma interro-negativa
Forma simple
couldn't I alter? couldn't you alter? couldn't he alter? couldn't we alter? couldn't you alter? couldn't they alter?
Forma con V-ing
couldn't I be altering? couldn't you be altering? couldn't he be altering? couldn't we be altering? couldn't you be altering? couldn't they be altering?
Perfecto
couldn't I have altered? couldn't you have altered? couldn't he have altered? couldn't we have altered? couldn't you have altered? couldn't they have altered?
Perfecto con V-ing
couldn't I have been altering? couldn't you have been altering? couldn't he have been altering? couldn't we have been altering? couldn't you have been altering? couldn't they have been altering?