English verb conjugation
COULD CHECKER

Regular verb: checker - checkered - checkered

Affirmation

Simple form	V-ing form
I could checker you could checker he could checker we could checker you could checker they could checker	I could be checkering you could be checkering he could be checkering we could be checkering you could be checkering they could be checkering
Perfect	V-ing perfect
I could have checkered you could have checkered he could have checkered we could have checkered you could have checkered they could have checkered	I could have been checkering you could have been checkering he could have been checkering we could have been checkering you could have been checkering they could have been checkering

Negation

Simple form	V-ing form
I could not checker you could not checker he could not checker we could not checker you could not checker they could not checker	I could not be checkering you could not be checkering he could not be checkering we could not be checkering you could not be checkering they could not be checkering
Perfect	V-ing perfect
I could not have checkered you could not have checkered he could not have checkered we could not have checkered you could not have checkered they could not have checkered	I could not have been checkering you could not have been checkering he could not have been checkering we could not have been checkering you could not have been checkering they could not have been checkering

Interrogative form

Simple form	V-ing form
could I checker? could you checker? could he checker? could we checker? could you checker? could they checker?	could I be checkering? could you be checkering? could he be checkering? could we be checkering? could you be checkering? could they be checkering?
Perfect	V-ing perfect
could I have checkered? could you have checkered? could he have checkered? could we have checkered? could you have checkered? could they have checkered?	could I have been checkering? could you have been checkering? could he have been checkering? could we have been checkering? could you have been checkering? could they have been checkering?

Interro-negative form

Simple form	V-ing form
could I not checker? could you not checker? could he not checker? could we not checker? could you not checker? could they not checker?	could I not be checkering? could you not be checkering? could he not be checkering? could we not be checkering? could you not be checkering? could they not be checkering?
Perfect	V-ing perfect
could I not have checkered? could you not have checkered? could he not have checkered? could we not have checkered? could you not have checkered? could they not have checkered?	could I not have been checkering? could you not have been checkering? could he not have been checkering? could we not have been checkering? could you not have been checkering? could they not have been checkering?