English verb conjugation
COULD SIFT

Regular verb: sift - sifted - sifted

Affirmation

Simple form	V-ing form
I could sift you could sift he could sift we could sift you could sift they could sift	I could be sifting you could be sifting he could be sifting we could be sifting you could be sifting they could be sifting
Perfect	V-ing perfect
I could have sifted you could have sifted he could have sifted we could have sifted you could have sifted they could have sifted	I could have been sifting you could have been sifting he could have been sifting we could have been sifting you could have been sifting they could have been sifting

Negation

Simple form	V-ing form
I couldn't sift you couldn't sift he couldn't sift we couldn't sift you couldn't sift they couldn't sift	I couldn't be sifting you couldn't be sifting he couldn't be sifting we couldn't be sifting you couldn't be sifting they couldn't be sifting
Perfect	V-ing perfect
I couldn't have sifted you couldn't have sifted he couldn't have sifted we couldn't have sifted you couldn't have sifted they couldn't have sifted	I couldn't have been sifting you couldn't have been sifting he couldn't have been sifting we couldn't have been sifting you couldn't have been sifting they couldn't have been sifting

Interrogative form

Simple form	V-ing form
could I sift? could you sift? could he sift? could we sift? could you sift? could they sift?	could I be sifting? could you be sifting? could he be sifting? could we be sifting? could you be sifting? could they be sifting?
Perfect	V-ing perfect
could I have sifted? could you have sifted? could he have sifted? could we have sifted? could you have sifted? could they have sifted?	could I have been sifting? could you have been sifting? could he have been sifting? could we have been sifting? could you have been sifting? could they have been sifting?

Interro-negative form

Simple form	V-ing form
couldn't I sift? couldn't you sift? couldn't he sift? couldn't we sift? couldn't you sift? couldn't they sift?	couldn't I be sifting? couldn't you be sifting? couldn't he be sifting? couldn't we be sifting? couldn't you be sifting? couldn't they be sifting?
Perfect	V-ing perfect
couldn't I have sifted? couldn't you have sifted? couldn't he have sifted? couldn't we have sifted? couldn't you have sifted? couldn't they have sifted?	couldn't I have been sifting? couldn't you have been sifting? couldn't he have been sifting? couldn't we have been sifting? couldn't you have been sifting? couldn't they have been sifting?