English verb conjugation
COULD PLUMB

Regular verb: plumb - plumbed - plumbed

Affirmation

Simple form	V-ing form
I could plumb you could plumb she could plumb we could plumb you could plumb they could plumb	I could be plumbing you could be plumbing she could be plumbing we could be plumbing you could be plumbing they could be plumbing
Perfect	V-ing perfect
I could have plumbed you could have plumbed she could have plumbed we could have plumbed you could have plumbed they could have plumbed	I could have been plumbing you could have been plumbing she could have been plumbing we could have been plumbing you could have been plumbing they could have been plumbing

Negation

Simple form	V-ing form
I could not plumb you could not plumb she could not plumb we could not plumb you could not plumb they could not plumb	I could not be plumbing you could not be plumbing she could not be plumbing we could not be plumbing you could not be plumbing they could not be plumbing
Perfect	V-ing perfect
I could not have plumbed you could not have plumbed she could not have plumbed we could not have plumbed you could not have plumbed they could not have plumbed	I could not have been plumbing you could not have been plumbing she could not have been plumbing we could not have been plumbing you could not have been plumbing they could not have been plumbing

Interrogative form

Simple form	V-ing form
could I plumb? could you plumb? could she plumb? could we plumb? could you plumb? could they plumb?	could I be plumbing? could you be plumbing? could she be plumbing? could we be plumbing? could you be plumbing? could they be plumbing?
Perfect	V-ing perfect
could I have plumbed? could you have plumbed? could she have plumbed? could we have plumbed? could you have plumbed? could they have plumbed?	could I have been plumbing? could you have been plumbing? could she have been plumbing? could we have been plumbing? could you have been plumbing? could they have been plumbing?

Interro-negative form

Simple form	V-ing form
could I not plumb? could you not plumb? could she not plumb? could we not plumb? could you not plumb? could they not plumb?	could I not be plumbing? could you not be plumbing? could she not be plumbing? could we not be plumbing? could you not be plumbing? could they not be plumbing?
Perfect	V-ing perfect
could I not have plumbed? could you not have plumbed? could she not have plumbed? could we not have plumbed? could you not have plumbed? could they not have plumbed?	could I not have been plumbing? could you not have been plumbing? could she not have been plumbing? could we not have been plumbing? could you not have been plumbing? could they not have been plumbing?