English verb conjugation
COULD PREFIX

Regular verb: prefix - prefixed - prefixed

Affirmation

Simple form	V-ing form
I could prefix you could prefix he could prefix we could prefix you could prefix they could prefix	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	V-ing 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	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	V-ing form
I couldn't prefix you couldn't prefix he couldn't prefix we couldn't prefix you couldn't prefix they couldn't prefix	I couldn't be prefixing you couldn't be prefixing he couldn't be prefixing we couldn't be prefixing you couldn't be prefixing they couldn't be prefixing
Perfect	V-ing perfect
I couldn't have prefixed you couldn't have prefixed he couldn't have prefixed we couldn't have prefixed you couldn't have prefixed they couldn't have prefixed	I couldn't have been prefixing you couldn't have been prefixing he couldn't have been prefixing we couldn't have been prefixing you couldn't have been prefixing they couldn't have been prefixing

Interrogative form

Simple form	V-ing form
could I prefix? could you prefix? could he prefix? could we prefix? could you prefix? could they prefix?	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	V-ing 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?	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	V-ing form
couldn't I prefix? couldn't you prefix? couldn't he prefix? couldn't we prefix? couldn't you prefix? couldn't they prefix?	couldn't I be prefixing? couldn't you be prefixing? couldn't he be prefixing? couldn't we be prefixing? couldn't you be prefixing? couldn't they be prefixing?
Perfect	V-ing perfect
couldn't I have prefixed? couldn't you have prefixed? couldn't he have prefixed? couldn't we have prefixed? couldn't you have prefixed? couldn't they have prefixed?	couldn't I have been prefixing? couldn't you have been prefixing? couldn't he have been prefixing? couldn't we have been prefixing? couldn't you have been prefixing? couldn't they have been prefixing?