I could graze you could graze he could graze we could graze you could graze they could graze
V-ing form
I could be grazing you could be grazing he could be grazing we could be grazing you could be grazing they could be grazing
Perfect
I could have grazed you could have grazed he could have grazed we could have grazed you could have grazed they could have grazed
V-ing perfect
I could have been grazing you could have been grazing he could have been grazing we could have been grazing you could have been grazing they could have been grazing
Negation
Simple form
I could not graze you could not graze he could not graze we could not graze you could not graze they could not graze
V-ing form
I could not be grazing you could not be grazing he could not be grazing we could not be grazing you could not be grazing they could not be grazing
Perfect
I could not have grazed you could not have grazed he could not have grazed we could not have grazed you could not have grazed they could not have grazed
V-ing perfect
I could not have been grazing you could not have been grazing he could not have been grazing we could not have been grazing you could not have been grazing they could not have been grazing
Interrogative form
Simple form
could I graze? could you graze? could he graze? could we graze? could you graze? could they graze?
V-ing form
could I be grazing? could you be grazing? could he be grazing? could we be grazing? could you be grazing? could they be grazing?
Perfect
could I have grazed? could you have grazed? could he have grazed? could we have grazed? could you have grazed? could they have grazed?
V-ing perfect
could I have been grazing? could you have been grazing? could he have been grazing? could we have been grazing? could you have been grazing? could they have been grazing?
Interro-negative form
Simple form
could I not graze? could you not graze? could he not graze? could we not graze? could you not graze? could they not graze?
V-ing form
could I not be grazing? could you not be grazing? could he not be grazing? could we not be grazing? could you not be grazing? could they not be grazing?
Perfect
could I not have grazed? could you not have grazed? could he not have grazed? could we not have grazed? could you not have grazed? could they not have grazed?
V-ing perfect
could I not have been grazing? could you not have been grazing? could he not have been grazing? could we not have been grazing? could you not have been grazing? could they not have been grazing?