I could frock you could frock she could frock we could frock you could frock they could frock
V-ing form
I could be frocking you could be frocking she could be frocking we could be frocking you could be frocking they could be frocking
Perfect
I could have frocked you could have frocked she could have frocked we could have frocked you could have frocked they could have frocked
V-ing perfect
I could have been frocking you could have been frocking she could have been frocking we could have been frocking you could have been frocking they could have been frocking
Negation
Simple form
I could not frock you could not frock she could not frock we could not frock you could not frock they could not frock
V-ing form
I could not be frocking you could not be frocking she could not be frocking we could not be frocking you could not be frocking they could not be frocking
Perfect
I could not have frocked you could not have frocked she could not have frocked we could not have frocked you could not have frocked they could not have frocked
V-ing perfect
I could not have been frocking you could not have been frocking she could not have been frocking we could not have been frocking you could not have been frocking they could not have been frocking
Interrogative form
Simple form
could I frock? could you frock? could she frock? could we frock? could you frock? could they frock?
V-ing form
could I be frocking? could you be frocking? could she be frocking? could we be frocking? could you be frocking? could they be frocking?
Perfect
could I have frocked? could you have frocked? could she have frocked? could we have frocked? could you have frocked? could they have frocked?
V-ing perfect
could I have been frocking? could you have been frocking? could she have been frocking? could we have been frocking? could you have been frocking? could they have been frocking?
Interro-negative form
Simple form
could I not frock? could you not frock? could she not frock? could we not frock? could you not frock? could they not frock?
V-ing form
could I not be frocking? could you not be frocking? could she not be frocking? could we not be frocking? could you not be frocking? could they not be frocking?
Perfect
could I not have frocked? could you not have frocked? could she not have frocked? could we not have frocked? could you not have frocked? could they not have frocked?
V-ing perfect
could I not have been frocking? could you not have been frocking? could she not have been frocking? could we not have been frocking? could you not have been frocking? could they not have been frocking?