I could bum you could bum she could bum we could bum you could bum they could bum
V-ing form
I could be bumming you could be bumming she could be bumming we could be bumming you could be bumming they could be bumming
Perfect
I could have bummed you could have bummed she could have bummed we could have bummed you could have bummed they could have bummed
V-ing perfect
I could have been bumming you could have been bumming she could have been bumming we could have been bumming you could have been bumming they could have been bumming
Negation
Simple form
I couldn't bum you couldn't bum she couldn't bum we couldn't bum you couldn't bum they couldn't bum
V-ing form
I couldn't be bumming you couldn't be bumming she couldn't be bumming we couldn't be bumming you couldn't be bumming they couldn't be bumming
Perfect
I couldn't have bummed you couldn't have bummed she couldn't have bummed we couldn't have bummed you couldn't have bummed they couldn't have bummed
V-ing perfect
I couldn't have been bumming you couldn't have been bumming she couldn't have been bumming we couldn't have been bumming you couldn't have been bumming they couldn't have been bumming
Interrogative form
Simple form
could I bum? could you bum? could she bum? could we bum? could you bum? could they bum?
V-ing form
could I be bumming? could you be bumming? could she be bumming? could we be bumming? could you be bumming? could they be bumming?
Perfect
could I have bummed? could you have bummed? could she have bummed? could we have bummed? could you have bummed? could they have bummed?
V-ing perfect
could I have been bumming? could you have been bumming? could she have been bumming? could we have been bumming? could you have been bumming? could they have been bumming?
Interro-negative form
Simple form
couldn't I bum? couldn't you bum? couldn't she bum? couldn't we bum? couldn't you bum? couldn't they bum?
V-ing form
couldn't I be bumming? couldn't you be bumming? couldn't she be bumming? couldn't we be bumming? couldn't you be bumming? couldn't they be bumming?
Perfect
couldn't I have bummed? couldn't you have bummed? couldn't she have bummed? couldn't we have bummed? couldn't you have bummed? couldn't they have bummed?
V-ing perfect
couldn't I have been bumming? couldn't you have been bumming? couldn't she have been bumming? couldn't we have been bumming? couldn't you have been bumming? couldn't they have been bumming?