I could fight you could fight she could fight we could fight you could fight they could fight
V-ing form
I could be fighting you could be fighting she could be fighting we could be fighting you could be fighting they could be fighting
Perfect
I could have fought you could have fought she could have fought we could have fought you could have fought they could have fought
V-ing perfect
I could have been fighting you could have been fighting she could have been fighting we could have been fighting you could have been fighting they could have been fighting
Negation
Simple form
I could not fight you could not fight she could not fight we could not fight you could not fight they could not fight
V-ing form
I could not be fighting you could not be fighting she could not be fighting we could not be fighting you could not be fighting they could not be fighting
Perfect
I could not have fought you could not have fought she could not have fought we could not have fought you could not have fought they could not have fought
V-ing perfect
I could not have been fighting you could not have been fighting she could not have been fighting we could not have been fighting you could not have been fighting they could not have been fighting
Interrogative form
Simple form
could I fight? could you fight? could she fight? could we fight? could you fight? could they fight?
V-ing form
could I be fighting? could you be fighting? could she be fighting? could we be fighting? could you be fighting? could they be fighting?
Perfect
could I have fought? could you have fought? could she have fought? could we have fought? could you have fought? could they have fought?
V-ing perfect
could I have been fighting? could you have been fighting? could she have been fighting? could we have been fighting? could you have been fighting? could they have been fighting?
Interro-negative form
Simple form
could I not fight? could you not fight? could she not fight? could we not fight? could you not fight? could they not fight?
V-ing form
could I not be fighting? could you not be fighting? could she not be fighting? could we not be fighting? could you not be fighting? could they not be fighting?
Perfect
could I not have fought? could you not have fought? could she not have fought? could we not have fought? could you not have fought? could they not have fought?
V-ing perfect
could I not have been fighting? could you not have been fighting? could she not have been fighting? could we not have been fighting? could you not have been fighting? could they not have been fighting?