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