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 couldn't plumb you couldn't plumb she couldn't plumb we couldn't plumb you couldn't plumb they couldn't plumb	I couldn't be plumbing you couldn't be plumbing she couldn't be plumbing we couldn't be plumbing you couldn't be plumbing they couldn't be plumbing
Perfect	V-ing perfect
I couldn't have plumbed you couldn't have plumbed she couldn't have plumbed we couldn't have plumbed you couldn't have plumbed they couldn't have plumbed	I couldn't have been plumbing you couldn't have been plumbing she couldn't have been plumbing we couldn't have been plumbing you couldn't have been plumbing they couldn't 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
couldn't I plumb? couldn't you plumb? couldn't she plumb? couldn't we plumb? couldn't you plumb? couldn't they plumb?	couldn't I be plumbing? couldn't you be plumbing? couldn't she be plumbing? couldn't we be plumbing? couldn't you be plumbing? couldn't they be plumbing?
Perfect	V-ing perfect
couldn't I have plumbed? couldn't you have plumbed? couldn't she have plumbed? couldn't we have plumbed? couldn't you have plumbed? couldn't they have plumbed?	couldn't I have been plumbing? couldn't you have been plumbing? couldn't she have been plumbing? couldn't we have been plumbing? couldn't you have been plumbing? couldn't they have been plumbing?