English verb conjugation
COULD RIB

Regular verb: rib - ribed - ribed

Affirmation

Simple form	V-ing form
I could rib you could rib he could rib we could rib you could rib they could rib	I could be ribing you could be ribing he could be ribing we could be ribing you could be ribing they could be ribing
Perfect	V-ing perfect
I could have ribed you could have ribed he could have ribed we could have ribed you could have ribed they could have ribed	I could have been ribing you could have been ribing he could have been ribing we could have been ribing you could have been ribing they could have been ribing

Negation

Simple form	V-ing form
I couldn't rib you couldn't rib he couldn't rib we couldn't rib you couldn't rib they couldn't rib	I couldn't be ribing you couldn't be ribing he couldn't be ribing we couldn't be ribing you couldn't be ribing they couldn't be ribing
Perfect	V-ing perfect
I couldn't have ribed you couldn't have ribed he couldn't have ribed we couldn't have ribed you couldn't have ribed they couldn't have ribed	I couldn't have been ribing you couldn't have been ribing he couldn't have been ribing we couldn't have been ribing you couldn't have been ribing they couldn't have been ribing

Interrogative form

Simple form	V-ing form
could I rib? could you rib? could he rib? could we rib? could you rib? could they rib?	could I be ribing? could you be ribing? could he be ribing? could we be ribing? could you be ribing? could they be ribing?
Perfect	V-ing perfect
could I have ribed? could you have ribed? could he have ribed? could we have ribed? could you have ribed? could they have ribed?	could I have been ribing? could you have been ribing? could he have been ribing? could we have been ribing? could you have been ribing? could they have been ribing?

Interro-negative form

Simple form	V-ing form
couldn't I rib? couldn't you rib? couldn't he rib? couldn't we rib? couldn't you rib? couldn't they rib?	couldn't I be ribing? couldn't you be ribing? couldn't he be ribing? couldn't we be ribing? couldn't you be ribing? couldn't they be ribing?
Perfect	V-ing perfect
couldn't I have ribed? couldn't you have ribed? couldn't he have ribed? couldn't we have ribed? couldn't you have ribed? couldn't they have ribed?	couldn't I have been ribing? couldn't you have been ribing? couldn't he have been ribing? couldn't we have been ribing? couldn't you have been ribing? couldn't they have been ribing?