I could grate you could grate he could grate we could grate you could grate they could grate
V-ing form
I could be grating you could be grating he could be grating we could be grating you could be grating they could be grating
Perfect
I could have grated you could have grated he could have grated we could have grated you could have grated they could have grated
V-ing perfect
I could have been grating you could have been grating he could have been grating we could have been grating you could have been grating they could have been grating
Negation
Simple form
I could not grate you could not grate he could not grate we could not grate you could not grate they could not grate
V-ing form
I could not be grating you could not be grating he could not be grating we could not be grating you could not be grating they could not be grating
Perfect
I could not have grated you could not have grated he could not have grated we could not have grated you could not have grated they could not have grated
V-ing perfect
I could not have been grating you could not have been grating he could not have been grating we could not have been grating you could not have been grating they could not have been grating
Interrogative form
Simple form
could I grate? could you grate? could he grate? could we grate? could you grate? could they grate?
V-ing form
could I be grating? could you be grating? could he be grating? could we be grating? could you be grating? could they be grating?
Perfect
could I have grated? could you have grated? could he have grated? could we have grated? could you have grated? could they have grated?
V-ing perfect
could I have been grating? could you have been grating? could he have been grating? could we have been grating? could you have been grating? could they have been grating?
Interro-negative form
Simple form
could I not grate? could you not grate? could he not grate? could we not grate? could you not grate? could they not grate?
V-ing form
could I not be grating? could you not be grating? could he not be grating? could we not be grating? could you not be grating? could they not be grating?
Perfect
could I not have grated? could you not have grated? could he not have grated? could we not have grated? could you not have grated? could they not have grated?
V-ing perfect
could I not have been grating? could you not have been grating? could he not have been grating? could we not have been grating? could you not have been grating? could they not have been grating?