I could polish you could polish she could polish we could polish you could polish they could polish
V-ing form
I could be polishing you could be polishing she could be polishing we could be polishing you could be polishing they could be polishing
Perfect
I could have polished you could have polished she could have polished we could have polished you could have polished they could have polished
V-ing perfect
I could have been polishing you could have been polishing she could have been polishing we could have been polishing you could have been polishing they could have been polishing
Negation
Simple form
I could not polish you could not polish she could not polish we could not polish you could not polish they could not polish
V-ing form
I could not be polishing you could not be polishing she could not be polishing we could not be polishing you could not be polishing they could not be polishing
Perfect
I could not have polished you could not have polished she could not have polished we could not have polished you could not have polished they could not have polished
V-ing perfect
I could not have been polishing you could not have been polishing she could not have been polishing we could not have been polishing you could not have been polishing they could not have been polishing
Interrogative form
Simple form
could I polish? could you polish? could she polish? could we polish? could you polish? could they polish?
V-ing form
could I be polishing? could you be polishing? could she be polishing? could we be polishing? could you be polishing? could they be polishing?
Perfect
could I have polished? could you have polished? could she have polished? could we have polished? could you have polished? could they have polished?
V-ing perfect
could I have been polishing? could you have been polishing? could she have been polishing? could we have been polishing? could you have been polishing? could they have been polishing?
Interro-negative form
Simple form
could I not polish? could you not polish? could she not polish? could we not polish? could you not polish? could they not polish?
V-ing form
could I not be polishing? could you not be polishing? could she not be polishing? could we not be polishing? could you not be polishing? could they not be polishing?
Perfect
could I not have polished? could you not have polished? could she not have polished? could we not have polished? could you not have polished? could they not have polished?
V-ing perfect
could I not have been polishing? could you not have been polishing? could she not have been polishing? could we not have been polishing? could you not have been polishing? could they not have been polishing?