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