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