I could adduct you could adduct he could adduct we could adduct you could adduct they could adduct
V-ing form
I could be adducting you could be adducting he could be adducting we could be adducting you could be adducting they could be adducting
Perfect
I could have adducted you could have adducted he could have adducted we could have adducted you could have adducted they could have adducted
V-ing perfect
I could have been adducting you could have been adducting he could have been adducting we could have been adducting you could have been adducting they could have been adducting
Negation
Simple form
I couldn't adduct you couldn't adduct he couldn't adduct we couldn't adduct you couldn't adduct they couldn't adduct
V-ing form
I couldn't be adducting you couldn't be adducting he couldn't be adducting we couldn't be adducting you couldn't be adducting they couldn't be adducting
Perfect
I couldn't have adducted you couldn't have adducted he couldn't have adducted we couldn't have adducted you couldn't have adducted they couldn't have adducted
V-ing perfect
I couldn't have been adducting you couldn't have been adducting he couldn't have been adducting we couldn't have been adducting you couldn't have been adducting they couldn't have been adducting
Interrogative form
Simple form
could I adduct? could you adduct? could he adduct? could we adduct? could you adduct? could they adduct?
V-ing form
could I be adducting? could you be adducting? could he be adducting? could we be adducting? could you be adducting? could they be adducting?
Perfect
could I have adducted? could you have adducted? could he have adducted? could we have adducted? could you have adducted? could they have adducted?
V-ing perfect
could I have been adducting? could you have been adducting? could he have been adducting? could we have been adducting? could you have been adducting? could they have been adducting?
Interro-negative form
Simple form
couldn't I adduct? couldn't you adduct? couldn't he adduct? couldn't we adduct? couldn't you adduct? couldn't they adduct?
V-ing form
couldn't I be adducting? couldn't you be adducting? couldn't he be adducting? couldn't we be adducting? couldn't you be adducting? couldn't they be adducting?
Perfect
couldn't I have adducted? couldn't you have adducted? couldn't he have adducted? couldn't we have adducted? couldn't you have adducted? couldn't they have adducted?
V-ing perfect
couldn't I have been adducting? couldn't you have been adducting? couldn't he have been adducting? couldn't we have been adducting? couldn't you have been adducting? couldn't they have been adducting?