I could swap you could swap he could swap we could swap you could swap they could swap
V-ing form
I could be swaping you could be swaping he could be swaping we could be swaping you could be swaping they could be swaping
Perfect
I could have swaped you could have swaped he could have swaped we could have swaped you could have swaped they could have swaped
V-ing perfect
I could have been swaping you could have been swaping he could have been swaping we could have been swaping you could have been swaping they could have been swaping
Negation
Simple form
I could not swap you could not swap he could not swap we could not swap you could not swap they could not swap
V-ing form
I could not be swaping you could not be swaping he could not be swaping we could not be swaping you could not be swaping they could not be swaping
Perfect
I could not have swaped you could not have swaped he could not have swaped we could not have swaped you could not have swaped they could not have swaped
V-ing perfect
I could not have been swaping you could not have been swaping he could not have been swaping we could not have been swaping you could not have been swaping they could not have been swaping
Interrogative form
Simple form
could I swap? could you swap? could he swap? could we swap? could you swap? could they swap?
V-ing form
could I be swaping? could you be swaping? could he be swaping? could we be swaping? could you be swaping? could they be swaping?
Perfect
could I have swaped? could you have swaped? could he have swaped? could we have swaped? could you have swaped? could they have swaped?
V-ing perfect
could I have been swaping? could you have been swaping? could he have been swaping? could we have been swaping? could you have been swaping? could they have been swaping?
Interro-negative form
Simple form
could I not swap? could you not swap? could he not swap? could we not swap? could you not swap? could they not swap?
V-ing form
could I not be swaping? could you not be swaping? could he not be swaping? could we not be swaping? could you not be swaping? could they not be swaping?
Perfect
could I not have swaped? could you not have swaped? could he not have swaped? could we not have swaped? could you not have swaped? could they not have swaped?
V-ing perfect
could I not have been swaping? could you not have been swaping? could he not have been swaping? could we not have been swaping? could you not have been swaping? could they not have been swaping?