I could prick you could prick she could prick we could prick you could prick they could prick
V-ing form
I could be pricking you could be pricking she could be pricking we could be pricking you could be pricking they could be pricking
Perfect
I could have pricked you could have pricked she could have pricked we could have pricked you could have pricked they could have pricked
V-ing perfect
I could have been pricking you could have been pricking she could have been pricking we could have been pricking you could have been pricking they could have been pricking
Negation
Simple form
I could not prick you could not prick she could not prick we could not prick you could not prick they could not prick
V-ing form
I could not be pricking you could not be pricking she could not be pricking we could not be pricking you could not be pricking they could not be pricking
Perfect
I could not have pricked you could not have pricked she could not have pricked we could not have pricked you could not have pricked they could not have pricked
V-ing perfect
I could not have been pricking you could not have been pricking she could not have been pricking we could not have been pricking you could not have been pricking they could not have been pricking
Interrogative form
Simple form
could I prick? could you prick? could she prick? could we prick? could you prick? could they prick?
V-ing form
could I be pricking? could you be pricking? could she be pricking? could we be pricking? could you be pricking? could they be pricking?
Perfect
could I have pricked? could you have pricked? could she have pricked? could we have pricked? could you have pricked? could they have pricked?
V-ing perfect
could I have been pricking? could you have been pricking? could she have been pricking? could we have been pricking? could you have been pricking? could they have been pricking?
Interro-negative form
Simple form
could I not prick? could you not prick? could she not prick? could we not prick? could you not prick? could they not prick?
V-ing form
could I not be pricking? could you not be pricking? could she not be pricking? could we not be pricking? could you not be pricking? could they not be pricking?
Perfect
could I not have pricked? could you not have pricked? could she not have pricked? could we not have pricked? could you not have pricked? could they not have pricked?
V-ing perfect
could I not have been pricking? could you not have been pricking? could she not have been pricking? could we not have been pricking? could you not have been pricking? could they not have been pricking?