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 couldn't swap you couldn't swap he couldn't swap we couldn't swap you couldn't swap they couldn't swap
V-ing form
I couldn't be swaping you couldn't be swaping he couldn't be swaping we couldn't be swaping you couldn't be swaping they couldn't be swaping
Perfect
I couldn't have swaped you couldn't have swaped he couldn't have swaped we couldn't have swaped you couldn't have swaped they couldn't have swaped
V-ing perfect
I couldn't have been swaping you couldn't have been swaping he couldn't have been swaping we couldn't have been swaping you couldn't have been swaping they couldn't 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
couldn't I swap? couldn't you swap? couldn't he swap? couldn't we swap? couldn't you swap? couldn't they swap?
V-ing form
couldn't I be swaping? couldn't you be swaping? couldn't he be swaping? couldn't we be swaping? couldn't you be swaping? couldn't they be swaping?
Perfect
couldn't I have swaped? couldn't you have swaped? couldn't he have swaped? couldn't we have swaped? couldn't you have swaped? couldn't they have swaped?
V-ing perfect
couldn't I have been swaping? couldn't you have been swaping? couldn't he have been swaping? couldn't we have been swaping? couldn't you have been swaping? couldn't they have been swaping?