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