I could gnaw you could gnaw she could gnaw we could gnaw you could gnaw they could gnaw
V-ing form
I could be gnawing you could be gnawing she could be gnawing we could be gnawing you could be gnawing they could be gnawing
Perfect
I could have gnawed you could have gnawed she 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 she could have been gnawing we could have been gnawing you could have been gnawing they could have been gnawing
Negation
Simple form
I couldn't gnaw you couldn't gnaw she couldn't gnaw we couldn't gnaw you couldn't gnaw they couldn't gnaw
V-ing form
I couldn't be gnawing you couldn't be gnawing she couldn't be gnawing we couldn't be gnawing you couldn't be gnawing they couldn't be gnawing
Perfect
I couldn't have gnawed you couldn't have gnawed she couldn't have gnawed we couldn't have gnawed you couldn't have gnawed they couldn't have gnawed
V-ing perfect
I couldn't have been gnawing you couldn't have been gnawing she couldn't have been gnawing we couldn't have been gnawing you couldn't have been gnawing they couldn't have been gnawing
Interrogative form
Simple form
could I gnaw? could you gnaw? could she gnaw? could we gnaw? could you gnaw? could they gnaw?
V-ing form
could I be gnawing? could you be gnawing? could she be gnawing? could we be gnawing? could you be gnawing? could they be gnawing?
Perfect
could I have gnawed? could you have gnawed? could she 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 she have been gnawing? could we have been gnawing? could you have been gnawing? could they have been gnawing?
Interro-negative form
Simple form
couldn't I gnaw? couldn't you gnaw? couldn't she gnaw? couldn't we gnaw? couldn't you gnaw? couldn't they gnaw?
V-ing form
couldn't I be gnawing? couldn't you be gnawing? couldn't she be gnawing? couldn't we be gnawing? couldn't you be gnawing? couldn't they be gnawing?
Perfect
couldn't I have gnawed? couldn't you have gnawed? couldn't she have gnawed? couldn't we have gnawed? couldn't you have gnawed? couldn't they have gnawed?
V-ing perfect
couldn't I have been gnawing? couldn't you have been gnawing? couldn't she have been gnawing? couldn't we have been gnawing? couldn't you have been gnawing? couldn't they have been gnawing?