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