I could stab you could stab he could stab we could stab you could stab they could stab
V-ing form
I could be stabbing you could be stabbing he could be stabbing we could be stabbing you could be stabbing they could be stabbing
Perfect
I could have stabbed you could have stabbed he could have stabbed we could have stabbed you could have stabbed they could have stabbed
V-ing perfect
I could have been stabbing you could have been stabbing he could have been stabbing we could have been stabbing you could have been stabbing they could have been stabbing
Negation
Simple form
I could not stab you could not stab he could not stab we could not stab you could not stab they could not stab
V-ing form
I could not be stabbing you could not be stabbing he could not be stabbing we could not be stabbing you could not be stabbing they could not be stabbing
Perfect
I could not have stabbed you could not have stabbed he could not have stabbed we could not have stabbed you could not have stabbed they could not have stabbed
V-ing perfect
I could not have been stabbing you could not have been stabbing he could not have been stabbing we could not have been stabbing you could not have been stabbing they could not have been stabbing
Interrogative form
Simple form
could I stab? could you stab? could he stab? could we stab? could you stab? could they stab?
V-ing form
could I be stabbing? could you be stabbing? could he be stabbing? could we be stabbing? could you be stabbing? could they be stabbing?
Perfect
could I have stabbed? could you have stabbed? could he have stabbed? could we have stabbed? could you have stabbed? could they have stabbed?
V-ing perfect
could I have been stabbing? could you have been stabbing? could he have been stabbing? could we have been stabbing? could you have been stabbing? could they have been stabbing?
Interro-negative form
Simple form
could I not stab? could you not stab? could he not stab? could we not stab? could you not stab? could they not stab?
V-ing form
could I not be stabbing? could you not be stabbing? could he not be stabbing? could we not be stabbing? could you not be stabbing? could they not be stabbing?
Perfect
could I not have stabbed? could you not have stabbed? could he not have stabbed? could we not have stabbed? could you not have stabbed? could they not have stabbed?
V-ing perfect
could I not have been stabbing? could you not have been stabbing? could he not have been stabbing? could we not have been stabbing? could you not have been stabbing? could they not have been stabbing?