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