could gnaw
Regular verb: gnaw - gnawed- gnawed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could gnaw
you could gnaw
she could gnaw
we could gnaw
you could gnaw
they could gnaw 	I could be gnawing
you could be gnawing
she could be gnawing
we could be gnawing
you could be gnawing
they could be gnawing	I could have gnawed
you could have gnawed
she could have gnawed
we could have gnawed
you could have gnawed
they could have gnawed	I could have been gnawing
you could have been gnawing
she could have been gnawing
we could have been gnawing
you could have been gnawing
they could have been gnawing	

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

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