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