I could kill you could kill he could kill we could kill you could kill they could kill
V-ing form
I could be killing you could be killing he could be killing we could be killing you could be killing they could be killing
Perfect
I could have killed you could have killed he could have killed we could have killed you could have killed they could have killed
V-ing perfect
I could have been killing you could have been killing he could have been killing we could have been killing you could have been killing they could have been killing
Negation
Simple form
I could not kill you could not kill he could not kill we could not kill you could not kill they could not kill
V-ing form
I could not be killing you could not be killing he could not be killing we could not be killing you could not be killing they could not be killing
Perfect
I could not have killed you could not have killed he could not have killed we could not have killed you could not have killed they could not have killed
V-ing perfect
I could not have been killing you could not have been killing he could not have been killing we could not have been killing you could not have been killing they could not have been killing
Interrogative form
Simple form
could I kill? could you kill? could he kill? could we kill? could you kill? could they kill?
V-ing form
could I be killing? could you be killing? could he be killing? could we be killing? could you be killing? could they be killing?
Perfect
could I have killed? could you have killed? could he have killed? could we have killed? could you have killed? could they have killed?
V-ing perfect
could I have been killing? could you have been killing? could he have been killing? could we have been killing? could you have been killing? could they have been killing?
Interro-negative form
Simple form
could I not kill? could you not kill? could he not kill? could we not kill? could you not kill? could they not kill?
V-ing form
could I not be killing? could you not be killing? could he not be killing? could we not be killing? could you not be killing? could they not be killing?
Perfect
could I not have killed? could you not have killed? could he not have killed? could we not have killed? could you not have killed? could they not have killed?
V-ing perfect
could I not have been killing? could you not have been killing? could he not have been killing? could we not have been killing? could you not have been killing? could they not have been killing?