I could prefix you could prefix he could prefix we could prefix you could prefix they could prefix
V-ing form
I could be prefixing you could be prefixing he could be prefixing we could be prefixing you could be prefixing they could be prefixing
Perfect
I could have prefixed you could have prefixed he could have prefixed we could have prefixed you could have prefixed they could have prefixed
V-ing perfect
I could have been prefixing you could have been prefixing he could have been prefixing we could have been prefixing you could have been prefixing they could have been prefixing
Negation
Simple form
I could not prefix you could not prefix he could not prefix we could not prefix you could not prefix they could not prefix
V-ing form
I could not be prefixing you could not be prefixing he could not be prefixing we could not be prefixing you could not be prefixing they could not be prefixing
Perfect
I could not have prefixed you could not have prefixed he could not have prefixed we could not have prefixed you could not have prefixed they could not have prefixed
V-ing perfect
I could not have been prefixing you could not have been prefixing he could not have been prefixing we could not have been prefixing you could not have been prefixing they could not have been prefixing
Interrogative form
Simple form
could I prefix? could you prefix? could he prefix? could we prefix? could you prefix? could they prefix?
V-ing form
could I be prefixing? could you be prefixing? could he be prefixing? could we be prefixing? could you be prefixing? could they be prefixing?
Perfect
could I have prefixed? could you have prefixed? could he have prefixed? could we have prefixed? could you have prefixed? could they have prefixed?
V-ing perfect
could I have been prefixing? could you have been prefixing? could he have been prefixing? could we have been prefixing? could you have been prefixing? could they have been prefixing?
Interro-negative form
Simple form
could I not prefix? could you not prefix? could he not prefix? could we not prefix? could you not prefix? could they not prefix?
V-ing form
could I not be prefixing? could you not be prefixing? could he not be prefixing? could we not be prefixing? could you not be prefixing? could they not be prefixing?
Perfect
could I not have prefixed? could you not have prefixed? could he not have prefixed? could we not have prefixed? could you not have prefixed? could they not have prefixed?
V-ing perfect
could I not have been prefixing? could you not have been prefixing? could he not have been prefixing? could we not have been prefixing? could you not have been prefixing? could they not have been prefixing?