English verb conjugation
COULD VALVE

Regular verb: valve - valved - valved

Affirmation

Simple form	V-ing form
I could valve you could valve he could valve we could valve you could valve they could valve	I could be valving you could be valving he could be valving we could be valving you could be valving they could be valving
Perfect	V-ing perfect
I could have valved you could have valved he could have valved we could have valved you could have valved they could have valved	I could have been valving you could have been valving he could have been valving we could have been valving you could have been valving they could have been valving

Negation

Simple form	V-ing form
I couldn't valve you couldn't valve he couldn't valve we couldn't valve you couldn't valve they couldn't valve	I couldn't be valving you couldn't be valving he couldn't be valving we couldn't be valving you couldn't be valving they couldn't be valving
Perfect	V-ing perfect
I couldn't have valved you couldn't have valved he couldn't have valved we couldn't have valved you couldn't have valved they couldn't have valved	I couldn't have been valving you couldn't have been valving he couldn't have been valving we couldn't have been valving you couldn't have been valving they couldn't have been valving

Interrogative form

Simple form	V-ing form
could I valve? could you valve? could he valve? could we valve? could you valve? could they valve?	could I be valving? could you be valving? could he be valving? could we be valving? could you be valving? could they be valving?
Perfect	V-ing perfect
could I have valved? could you have valved? could he have valved? could we have valved? could you have valved? could they have valved?	could I have been valving? could you have been valving? could he have been valving? could we have been valving? could you have been valving? could they have been valving?

Interro-negative form

Simple form	V-ing form
couldn't I valve? couldn't you valve? couldn't he valve? couldn't we valve? couldn't you valve? couldn't they valve?	couldn't I be valving? couldn't you be valving? couldn't he be valving? couldn't we be valving? couldn't you be valving? couldn't they be valving?
Perfect	V-ing perfect
couldn't I have valved? couldn't you have valved? couldn't he have valved? couldn't we have valved? couldn't you have valved? couldn't they have valved?	couldn't I have been valving? couldn't you have been valving? couldn't he have been valving? couldn't we have been valving? couldn't you have been valving? couldn't they have been valving?