I could gnaw you could gnaw he could gnaw we could gnaw you could gnaw they could gnaw
V-ing form
I could be gnawing you could be gnawing he could be gnawing we could be gnawing you could be gnawing they could be gnawing
Perfect
I could have gnawed you could have gnawed he could have gnawed we could have gnawed you could have gnawed they could have gnawed
V-ing perfect
I could have been gnawing you could have been gnawing he could have been gnawing we could have been gnawing you could have been gnawing they could have been gnawing
Negation
Simple form
I could not gnaw you could not gnaw he could not gnaw we could not gnaw you could not gnaw they could not gnaw
V-ing form
I could not be gnawing you could not be gnawing he could not be gnawing we could not be gnawing you could not be gnawing they could not be gnawing
Perfect
I could not have gnawed you could not have gnawed he could not have gnawed we could not have gnawed you could not have gnawed they could not have gnawed
V-ing perfect
I could not have been gnawing you could not have been gnawing he could not have been gnawing we could not have been gnawing you could not have been gnawing they could not have been gnawing
Interrogative form
Simple form
could I gnaw? could you gnaw? could he gnaw? could we gnaw? could you gnaw? could they gnaw?
V-ing form
could I be gnawing? could you be gnawing? could he be gnawing? could we be gnawing? could you be gnawing? could they be gnawing?
Perfect
could I have gnawed? could you have gnawed? could he have gnawed? could we have gnawed? could you have gnawed? could they have gnawed?
V-ing perfect
could I have been gnawing? could you have been gnawing? could he have been gnawing? could we have been gnawing? could you have been gnawing? could they have been gnawing?
Interro-negative form
Simple form
could I not gnaw? could you not gnaw? could he not gnaw? could we not gnaw? could you not gnaw? could they not gnaw?
V-ing form
could I not be gnawing? could you not be gnawing? could he not be gnawing? could we not be gnawing? could you not be gnawing? could they not be gnawing?
Perfect
could I not have gnawed? could you not have gnawed? could he not have gnawed? could we not have gnawed? could you not have gnawed? could they not have gnawed?
V-ing perfect
could I not have been gnawing? could you not have been gnawing? could he not have been gnawing? could we not have been gnawing? could you not have been gnawing? could they not have been gnawing?