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