I could sift you could sift she could sift we could sift you could sift they could sift
Forma con V-ing
I could be sifting you could be sifting she could be sifting we could be sifting you could be sifting they could be sifting
Perfecto
I could have sifted you could have sifted she could have sifted we could have sifted you could have sifted they could have sifted
Perfecto con V-ing
I could have been sifting you could have been sifting she could have been sifting we could have been sifting you could have been sifting they could have been sifting
Negación
Forma simple
I couldn't sift you couldn't sift she couldn't sift we couldn't sift you couldn't sift they couldn't sift
Forma con V-ing
I couldn't be sifting you couldn't be sifting she couldn't be sifting we couldn't be sifting you couldn't be sifting they couldn't be sifting
Perfecto
I couldn't have sifted you couldn't have sifted she couldn't have sifted we couldn't have sifted you couldn't have sifted they couldn't have sifted
Perfecto con V-ing
I couldn't have been sifting you couldn't have been sifting she couldn't have been sifting we couldn't have been sifting you couldn't have been sifting they couldn't have been sifting
Forma interrogativa
Forma simple
could I sift? could you sift? could she sift? could we sift? could you sift? could they sift?
Forma con V-ing
could I be sifting? could you be sifting? could she be sifting? could we be sifting? could you be sifting? could they be sifting?
Perfecto
could I have sifted? could you have sifted? could she have sifted? could we have sifted? could you have sifted? could they have sifted?
Perfecto con V-ing
could I have been sifting? could you have been sifting? could she have been sifting? could we have been sifting? could you have been sifting? could they have been sifting?
Forma interro-negativa
Forma simple
couldn't I sift? couldn't you sift? couldn't she sift? couldn't we sift? couldn't you sift? couldn't they sift?
Forma con V-ing
couldn't I be sifting? couldn't you be sifting? couldn't she be sifting? couldn't we be sifting? couldn't you be sifting? couldn't they be sifting?
Perfecto
couldn't I have sifted? couldn't you have sifted? couldn't she have sifted? couldn't we have sifted? couldn't you have sifted? couldn't they have sifted?
Perfecto con V-ing
couldn't I have been sifting? couldn't you have been sifting? couldn't she have been sifting? couldn't we have been sifting? couldn't you have been sifting? couldn't they have been sifting?