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