I could flat you could flat he could flat we could flat you could flat they could flat
V-ing form
I could be flating you could be flating he could be flating we could be flating you could be flating they could be flating
Perfect
I could have flated you could have flated he 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 he could have been flating we could have been flating you could have been flating they could have been flating
Negation
Simple form
I could not flat you could not flat he could not flat we could not flat you could not flat they could not flat
V-ing form
I could not be flating you could not be flating he could not be flating we could not be flating you could not be flating they could not be flating
Perfect
I could not have flated you could not have flated he could not have flated we could not have flated you could not have flated they could not have flated
V-ing perfect
I could not have been flating you could not have been flating he could not have been flating we could not have been flating you could not have been flating they could not have been flating
Interrogative form
Simple form
could I flat? could you flat? could he flat? could we flat? could you flat? could they flat?
V-ing form
could I be flating? could you be flating? could he be flating? could we be flating? could you be flating? could they be flating?
Perfect
could I have flated? could you have flated? could he 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 he have been flating? could we have been flating? could you have been flating? could they have been flating?
Interro-negative form
Simple form
could I not flat? could you not flat? could he not flat? could we not flat? could you not flat? could they not flat?
V-ing form
could I not be flating? could you not be flating? could he not be flating? could we not be flating? could you not be flating? could they not be flating?
Perfect
could I not have flated? could you not have flated? could he not have flated? could we not have flated? could you not have flated? could they not have flated?
V-ing perfect
could I not have been flating? could you not have been flating? could he not have been flating? could we not have been flating? could you not have been flating? could they not have been flating?