I could differ you could differ she could differ we could differ you could differ they could differ
V-ing form
I could be differing you could be differing she could be differing we could be differing you could be differing they could be differing
Perfect
I could have differed you could have differed she could have differed we could have differed you could have differed they could have differed
V-ing perfect
I could have been differing you could have been differing she could have been differing we could have been differing you could have been differing they could have been differing
Negation
Simple form
I couldn't differ you couldn't differ she couldn't differ we couldn't differ you couldn't differ they couldn't differ
V-ing form
I couldn't be differing you couldn't be differing she couldn't be differing we couldn't be differing you couldn't be differing they couldn't be differing
Perfect
I couldn't have differed you couldn't have differed she couldn't have differed we couldn't have differed you couldn't have differed they couldn't have differed
V-ing perfect
I couldn't have been differing you couldn't have been differing she couldn't have been differing we couldn't have been differing you couldn't have been differing they couldn't have been differing
Interrogative form
Simple form
could I differ? could you differ? could she differ? could we differ? could you differ? could they differ?
V-ing form
could I be differing? could you be differing? could she be differing? could we be differing? could you be differing? could they be differing?
Perfect
could I have differed? could you have differed? could she have differed? could we have differed? could you have differed? could they have differed?
V-ing perfect
could I have been differing? could you have been differing? could she have been differing? could we have been differing? could you have been differing? could they have been differing?
Interro-negative form
Simple form
couldn't I differ? couldn't you differ? couldn't she differ? couldn't we differ? couldn't you differ? couldn't they differ?
V-ing form
couldn't I be differing? couldn't you be differing? couldn't she be differing? couldn't we be differing? couldn't you be differing? couldn't they be differing?
Perfect
couldn't I have differed? couldn't you have differed? couldn't she have differed? couldn't we have differed? couldn't you have differed? couldn't they have differed?
V-ing perfect
couldn't I have been differing? couldn't you have been differing? couldn't she have been differing? couldn't we have been differing? couldn't you have been differing? couldn't they have been differing?