I could chat you could chat he could chat we could chat you could chat they could chat
V-ing form
I could be chatting you could be chatting he could be chatting we could be chatting you could be chatting they could be chatting
Perfect
I could have chatted you could have chatted he could have chatted we could have chatted you could have chatted they could have chatted
V-ing perfect
I could have been chatting you could have been chatting he could have been chatting we could have been chatting you could have been chatting they could have been chatting
Negation
Simple form
I could not chat you could not chat he could not chat we could not chat you could not chat they could not chat
V-ing form
I could not be chatting you could not be chatting he could not be chatting we could not be chatting you could not be chatting they could not be chatting
Perfect
I could not have chatted you could not have chatted he could not have chatted we could not have chatted you could not have chatted they could not have chatted
V-ing perfect
I could not have been chatting you could not have been chatting he could not have been chatting we could not have been chatting you could not have been chatting they could not have been chatting
Interrogative form
Simple form
could I chat? could you chat? could he chat? could we chat? could you chat? could they chat?
V-ing form
could I be chatting? could you be chatting? could he be chatting? could we be chatting? could you be chatting? could they be chatting?
Perfect
could I have chatted? could you have chatted? could he have chatted? could we have chatted? could you have chatted? could they have chatted?
V-ing perfect
could I have been chatting? could you have been chatting? could he have been chatting? could we have been chatting? could you have been chatting? could they have been chatting?
Interro-negative form
Simple form
could I not chat? could you not chat? could he not chat? could we not chat? could you not chat? could they not chat?
V-ing form
could I not be chatting? could you not be chatting? could he not be chatting? could we not be chatting? could you not be chatting? could they not be chatting?
Perfect
could I not have chatted? could you not have chatted? could he not have chatted? could we not have chatted? could you not have chatted? could they not have chatted?
V-ing perfect
could I not have been chatting? could you not have been chatting? could he not have been chatting? could we not have been chatting? could you not have been chatting? could they not have been chatting?