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