I could hem you could hem he could hem we could hem you could hem they could hem
V-ing form
I could be hemming you could be hemming he could be hemming we could be hemming you could be hemming they could be hemming
Perfect
I could have hemmed you could have hemmed he 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 he 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 he 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 he 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 he 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 he 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 he hem? could we hem? could you hem? could they hem?
V-ing form
could I be hemming? could you be hemming? could he be hemming? could we be hemming? could you be hemming? could they be hemming?
Perfect
could I have hemmed? could you have hemmed? could he 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 he 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 he 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 he 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 he 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 he have been hemming? couldn't we have been hemming? couldn't you have been hemming? couldn't they have been hemming?