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