I could fox you could fox she could fox we could fox you could fox they could fox
V-ing form
I could be foxing you could be foxing she could be foxing we could be foxing you could be foxing they could be foxing
Perfect
I could have foxed you could have foxed she could have foxed we could have foxed you could have foxed they could have foxed
V-ing perfect
I could have been foxing you could have been foxing she could have been foxing we could have been foxing you could have been foxing they could have been foxing
Negation
Simple form
I could not fox you could not fox she could not fox we could not fox you could not fox they could not fox
V-ing form
I could not be foxing you could not be foxing she could not be foxing we could not be foxing you could not be foxing they could not be foxing
Perfect
I could not have foxed you could not have foxed she could not have foxed we could not have foxed you could not have foxed they could not have foxed
V-ing perfect
I could not have been foxing you could not have been foxing she could not have been foxing we could not have been foxing you could not have been foxing they could not have been foxing
Interrogative form
Simple form
could I fox? could you fox? could she fox? could we fox? could you fox? could they fox?
V-ing form
could I be foxing? could you be foxing? could she be foxing? could we be foxing? could you be foxing? could they be foxing?
Perfect
could I have foxed? could you have foxed? could she have foxed? could we have foxed? could you have foxed? could they have foxed?
V-ing perfect
could I have been foxing? could you have been foxing? could she have been foxing? could we have been foxing? could you have been foxing? could they have been foxing?
Interro-negative form
Simple form
could I not fox? could you not fox? could she not fox? could we not fox? could you not fox? could they not fox?
V-ing form
could I not be foxing? could you not be foxing? could she not be foxing? could we not be foxing? could you not be foxing? could they not be foxing?
Perfect
could I not have foxed? could you not have foxed? could she not have foxed? could we not have foxed? could you not have foxed? could they not have foxed?
V-ing perfect
could I not have been foxing? could you not have been foxing? could she not have been foxing? could we not have been foxing? could you not have been foxing? could they not have been foxing?