I could wall you could wall she could wall we could wall you could wall they could wall
V-ing form
I could be walling you could be walling she could be walling we could be walling you could be walling they could be walling
Perfect
I could have walled you could have walled she could have walled we could have walled you could have walled they could have walled
V-ing perfect
I could have been walling you could have been walling she could have been walling we could have been walling you could have been walling they could have been walling
Negation
Simple form
I could not wall you could not wall she could not wall we could not wall you could not wall they could not wall
V-ing form
I could not be walling you could not be walling she could not be walling we could not be walling you could not be walling they could not be walling
Perfect
I could not have walled you could not have walled she could not have walled we could not have walled you could not have walled they could not have walled
V-ing perfect
I could not have been walling you could not have been walling she could not have been walling we could not have been walling you could not have been walling they could not have been walling
Interrogative form
Simple form
could I wall? could you wall? could she wall? could we wall? could you wall? could they wall?
V-ing form
could I be walling? could you be walling? could she be walling? could we be walling? could you be walling? could they be walling?
Perfect
could I have walled? could you have walled? could she have walled? could we have walled? could you have walled? could they have walled?
V-ing perfect
could I have been walling? could you have been walling? could she have been walling? could we have been walling? could you have been walling? could they have been walling?
Interro-negative form
Simple form
could I not wall? could you not wall? could she not wall? could we not wall? could you not wall? could they not wall?
V-ing form
could I not be walling? could you not be walling? could she not be walling? could we not be walling? could you not be walling? could they not be walling?
Perfect
could I not have walled? could you not have walled? could she not have walled? could we not have walled? could you not have walled? could they not have walled?
V-ing perfect
could I not have been walling? could you not have been walling? could she not have been walling? could we not have been walling? could you not have been walling? could they not have been walling?