English verb conjugation
COULD BIFF

Regular verb: biff - biffed - biffed

Affirmation

Simple form	V-ing form
I could biff you could biff he could biff we could biff you could biff they could biff	I could be biffing you could be biffing he could be biffing we could be biffing you could be biffing they could be biffing
Perfect	V-ing perfect
I could have biffed you could have biffed he could have biffed we could have biffed you could have biffed they could have biffed	I could have been biffing you could have been biffing he could have been biffing we could have been biffing you could have been biffing they could have been biffing

Negation

Simple form	V-ing form
I could not biff you could not biff he could not biff we could not biff you could not biff they could not biff	I could not be biffing you could not be biffing he could not be biffing we could not be biffing you could not be biffing they could not be biffing
Perfect	V-ing perfect
I could not have biffed you could not have biffed he could not have biffed we could not have biffed you could not have biffed they could not have biffed	I could not have been biffing you could not have been biffing he could not have been biffing we could not have been biffing you could not have been biffing they could not have been biffing

Interrogative form

Simple form	V-ing form
could I biff? could you biff? could he biff? could we biff? could you biff? could they biff?	could I be biffing? could you be biffing? could he be biffing? could we be biffing? could you be biffing? could they be biffing?
Perfect	V-ing perfect
could I have biffed? could you have biffed? could he have biffed? could we have biffed? could you have biffed? could they have biffed?	could I have been biffing? could you have been biffing? could he have been biffing? could we have been biffing? could you have been biffing? could they have been biffing?

Interro-negative form

Simple form	V-ing form
could I not biff? could you not biff? could he not biff? could we not biff? could you not biff? could they not biff?	could I not be biffing? could you not be biffing? could he not be biffing? could we not be biffing? could you not be biffing? could they not be biffing?
Perfect	V-ing perfect
could I not have biffed? could you not have biffed? could he not have biffed? could we not have biffed? could you not have biffed? could they not have biffed?	could I not have been biffing? could you not have been biffing? could he not have been biffing? could we not have been biffing? could you not have been biffing? could they not have been biffing?