English verb conjugation
COULD DIFFER

Regular verb: differ - differed - differed

Affirmation

Simple form	V-ing form
I could differ you could differ he could differ we could differ you could differ they could differ	I could be differing you could be differing he could be differing we could be differing you could be differing they could be differing
Perfect	V-ing perfect
I could have differed you could have differed he could have differed we could have differed you could have differed they could have differed	I could have been differing you could have been differing he could have been differing we could have been differing you could have been differing they could have been differing

Negation

Simple form	V-ing form
I couldn't differ you couldn't differ he couldn't differ we couldn't differ you couldn't differ they couldn't differ	I couldn't be differing you couldn't be differing he couldn't be differing we couldn't be differing you couldn't be differing they couldn't be differing
Perfect	V-ing perfect
I couldn't have differed you couldn't have differed he couldn't have differed we couldn't have differed you couldn't have differed they couldn't have differed	I couldn't have been differing you couldn't have been differing he 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	V-ing form
could I differ? could you differ? could he differ? could we differ? could you differ? could they differ?	could I be differing? could you be differing? could he be differing? could we be differing? could you be differing? could they be differing?
Perfect	V-ing perfect
could I have differed? could you have differed? could he have differed? could we have differed? could you have differed? could they have differed?	could I have been differing? could you have been differing? could he have been differing? could we have been differing? could you have been differing? could they have been differing?

Interro-negative form

Simple form	V-ing form
couldn't I differ? couldn't you differ? couldn't he differ? couldn't we differ? couldn't you differ? couldn't they differ?	couldn't I be differing? couldn't you be differing? couldn't he be differing? couldn't we be differing? couldn't you be differing? couldn't they be differing?
Perfect	V-ing perfect
couldn't I have differed? couldn't you have differed? couldn't he have differed? couldn't we have differed? couldn't you have differed? couldn't they have differed?	couldn't I have been differing? couldn't you have been differing? couldn't he have been differing? couldn't we have been differing? couldn't you have been differing? couldn't they have been differing?