I could strum you could strum he could strum we could strum you could strum they could strum
V-ing form
I could be strumming you could be strumming he could be strumming we could be strumming you could be strumming they could be strumming
Perfect
I could have strummed you could have strummed he could have strummed we could have strummed you could have strummed they could have strummed
V-ing perfect
I could have been strumming you could have been strumming he could have been strumming we could have been strumming you could have been strumming they could have been strumming
Negation
Simple form
I couldn't strum you couldn't strum he couldn't strum we couldn't strum you couldn't strum they couldn't strum
V-ing form
I couldn't be strumming you couldn't be strumming he couldn't be strumming we couldn't be strumming you couldn't be strumming they couldn't be strumming
Perfect
I couldn't have strummed you couldn't have strummed he couldn't have strummed we couldn't have strummed you couldn't have strummed they couldn't have strummed
V-ing perfect
I couldn't have been strumming you couldn't have been strumming he couldn't have been strumming we couldn't have been strumming you couldn't have been strumming they couldn't have been strumming
Interrogative form
Simple form
could I strum? could you strum? could he strum? could we strum? could you strum? could they strum?
V-ing form
could I be strumming? could you be strumming? could he be strumming? could we be strumming? could you be strumming? could they be strumming?
Perfect
could I have strummed? could you have strummed? could he have strummed? could we have strummed? could you have strummed? could they have strummed?
V-ing perfect
could I have been strumming? could you have been strumming? could he have been strumming? could we have been strumming? could you have been strumming? could they have been strumming?
Interro-negative form
Simple form
couldn't I strum? couldn't you strum? couldn't he strum? couldn't we strum? couldn't you strum? couldn't they strum?
V-ing form
couldn't I be strumming? couldn't you be strumming? couldn't he be strumming? couldn't we be strumming? couldn't you be strumming? couldn't they be strumming?
Perfect
couldn't I have strummed? couldn't you have strummed? couldn't he have strummed? couldn't we have strummed? couldn't you have strummed? couldn't they have strummed?
V-ing perfect
couldn't I have been strumming? couldn't you have been strumming? couldn't he have been strumming? couldn't we have been strumming? couldn't you have been strumming? couldn't they have been strumming?