I could preface you could preface she could preface we could preface you could preface they could preface
V-ing form
I could be prefacing you could be prefacing she could be prefacing we could be prefacing you could be prefacing they could be prefacing
Perfect
I could have prefaced you could have prefaced she could have prefaced we could have prefaced you could have prefaced they could have prefaced
V-ing perfect
I could have been prefacing you could have been prefacing she could have been prefacing we could have been prefacing you could have been prefacing they could have been prefacing
Negation
Simple form
I could not preface you could not preface she could not preface we could not preface you could not preface they could not preface
V-ing form
I could not be prefacing you could not be prefacing she could not be prefacing we could not be prefacing you could not be prefacing they could not be prefacing
Perfect
I could not have prefaced you could not have prefaced she could not have prefaced we could not have prefaced you could not have prefaced they could not have prefaced
V-ing perfect
I could not have been prefacing you could not have been prefacing she could not have been prefacing we could not have been prefacing you could not have been prefacing they could not have been prefacing
Interrogative form
Simple form
could I preface? could you preface? could she preface? could we preface? could you preface? could they preface?
V-ing form
could I be prefacing? could you be prefacing? could she be prefacing? could we be prefacing? could you be prefacing? could they be prefacing?
Perfect
could I have prefaced? could you have prefaced? could she have prefaced? could we have prefaced? could you have prefaced? could they have prefaced?
V-ing perfect
could I have been prefacing? could you have been prefacing? could she have been prefacing? could we have been prefacing? could you have been prefacing? could they have been prefacing?
Interro-negative form
Simple form
could I not preface? could you not preface? could she not preface? could we not preface? could you not preface? could they not preface?
V-ing form
could I not be prefacing? could you not be prefacing? could she not be prefacing? could we not be prefacing? could you not be prefacing? could they not be prefacing?
Perfect
could I not have prefaced? could you not have prefaced? could she not have prefaced? could we not have prefaced? could you not have prefaced? could they not have prefaced?
V-ing perfect
could I not have been prefacing? could you not have been prefacing? could she not have been prefacing? could we not have been prefacing? could you not have been prefacing? could they not have been prefacing?