I could off you could off he could off we could off you could off they could off
V-ing form
I could be offing you could be offing he could be offing we could be offing you could be offing they could be offing
Perfect
I could have offed you could have offed he could have offed we could have offed you could have offed they could have offed
V-ing perfect
I could have been offing you could have been offing he could have been offing we could have been offing you could have been offing they could have been offing
Negation
Simple form
I couldn't off you couldn't off he couldn't off we couldn't off you couldn't off they couldn't off
V-ing form
I couldn't be offing you couldn't be offing he couldn't be offing we couldn't be offing you couldn't be offing they couldn't be offing
Perfect
I couldn't have offed you couldn't have offed he couldn't have offed we couldn't have offed you couldn't have offed they couldn't have offed
V-ing perfect
I couldn't have been offing you couldn't have been offing he couldn't have been offing we couldn't have been offing you couldn't have been offing they couldn't have been offing
Interrogative form
Simple form
could I off? could you off? could he off? could we off? could you off? could they off?
V-ing form
could I be offing? could you be offing? could he be offing? could we be offing? could you be offing? could they be offing?
Perfect
could I have offed? could you have offed? could he have offed? could we have offed? could you have offed? could they have offed?
V-ing perfect
could I have been offing? could you have been offing? could he have been offing? could we have been offing? could you have been offing? could they have been offing?
Interro-negative form
Simple form
couldn't I off? couldn't you off? couldn't he off? couldn't we off? couldn't you off? couldn't they off?
V-ing form
couldn't I be offing? couldn't you be offing? couldn't he be offing? couldn't we be offing? couldn't you be offing? couldn't they be offing?
Perfect
couldn't I have offed? couldn't you have offed? couldn't he have offed? couldn't we have offed? couldn't you have offed? couldn't they have offed?
V-ing perfect
couldn't I have been offing? couldn't you have been offing? couldn't he have been offing? couldn't we have been offing? couldn't you have been offing? couldn't they have been offing?