I could flatten you could flatten she could flatten we could flatten you could flatten they could flatten
V-ing form
I could be flattening you could be flattening she could be flattening we could be flattening you could be flattening they could be flattening
Perfect
I could have flattened you could have flattened she could have flattened we could have flattened you could have flattened they could have flattened
V-ing perfect
I could have been flattening you could have been flattening she could have been flattening we could have been flattening you could have been flattening they could have been flattening
Negation
Simple form
I could not flatten you could not flatten she could not flatten we could not flatten you could not flatten they could not flatten
V-ing form
I could not be flattening you could not be flattening she could not be flattening we could not be flattening you could not be flattening they could not be flattening
Perfect
I could not have flattened you could not have flattened she could not have flattened we could not have flattened you could not have flattened they could not have flattened
V-ing perfect
I could not have been flattening you could not have been flattening she could not have been flattening we could not have been flattening you could not have been flattening they could not have been flattening
Interrogative form
Simple form
could I flatten? could you flatten? could she flatten? could we flatten? could you flatten? could they flatten?
V-ing form
could I be flattening? could you be flattening? could she be flattening? could we be flattening? could you be flattening? could they be flattening?
Perfect
could I have flattened? could you have flattened? could she have flattened? could we have flattened? could you have flattened? could they have flattened?
V-ing perfect
could I have been flattening? could you have been flattening? could she have been flattening? could we have been flattening? could you have been flattening? could they have been flattening?
Interro-negative form
Simple form
could I not flatten? could you not flatten? could she not flatten? could we not flatten? could you not flatten? could they not flatten?
V-ing form
could I not be flattening? could you not be flattening? could she not be flattening? could we not be flattening? could you not be flattening? could they not be flattening?
Perfect
could I not have flattened? could you not have flattened? could she not have flattened? could we not have flattened? could you not have flattened? could they not have flattened?
V-ing perfect
could I not have been flattening? could you not have been flattening? could she not have been flattening? could we not have been flattening? could you not have been flattening? could they not have been flattening?