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