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 could not mat you could not mat he could not mat we could not mat you could not mat they could not mat
V-ing form
I could not be matting you could not be matting he could not be matting we could not be matting you could not be matting they could not be matting
Perfect
I could not have matted you could not have matted he could not have matted we could not have matted you could not have matted they could not have matted
V-ing perfect
I could not have been matting you could not have been matting he could not have been matting we could not have been matting you could not have been matting they could not 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
could I not mat? could you not mat? could he not mat? could we not mat? could you not mat? could they not mat?
V-ing form
could I not be matting? could you not be matting? could he not be matting? could we not be matting? could you not be matting? could they not be matting?
Perfect
could I not have matted? could you not have matted? could he not have matted? could we not have matted? could you not have matted? could they not have matted?
V-ing perfect
could I not have been matting? could you not have been matting? could he not have been matting? could we not have been matting? could you not have been matting? could they not have been matting?