I could interchange you could interchange he could interchange we could interchange you could interchange they could interchange
V-ing form
I could be interchanging you could be interchanging he could be interchanging we could be interchanging you could be interchanging they could be interchanging
Perfect
I could have interchanged you could have interchanged he could have interchanged we could have interchanged you could have interchanged they could have interchanged
V-ing perfect
I could have been interchanging you could have been interchanging he could have been interchanging we could have been interchanging you could have been interchanging they could have been interchanging
Negation
Simple form
I could not interchange you could not interchange he could not interchange we could not interchange you could not interchange they could not interchange
V-ing form
I could not be interchanging you could not be interchanging he could not be interchanging we could not be interchanging you could not be interchanging they could not be interchanging
Perfect
I could not have interchanged you could not have interchanged he could not have interchanged we could not have interchanged you could not have interchanged they could not have interchanged
V-ing perfect
I could not have been interchanging you could not have been interchanging he could not have been interchanging we could not have been interchanging you could not have been interchanging they could not have been interchanging
Interrogative form
Simple form
could I interchange? could you interchange? could he interchange? could we interchange? could you interchange? could they interchange?
V-ing form
could I be interchanging? could you be interchanging? could he be interchanging? could we be interchanging? could you be interchanging? could they be interchanging?
Perfect
could I have interchanged? could you have interchanged? could he have interchanged? could we have interchanged? could you have interchanged? could they have interchanged?
V-ing perfect
could I have been interchanging? could you have been interchanging? could he have been interchanging? could we have been interchanging? could you have been interchanging? could they have been interchanging?
Interro-negative form
Simple form
could I not interchange? could you not interchange? could he not interchange? could we not interchange? could you not interchange? could they not interchange?
V-ing form
could I not be interchanging? could you not be interchanging? could he not be interchanging? could we not be interchanging? could you not be interchanging? could they not be interchanging?
Perfect
could I not have interchanged? could you not have interchanged? could he not have interchanged? could we not have interchanged? could you not have interchanged? could they not have interchanged?
V-ing perfect
could I not have been interchanging? could you not have been interchanging? could he not have been interchanging? could we not have been interchanging? could you not have been interchanging? could they not have been interchanging?