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