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