I could pen you could pen she could pen we could pen you could pen they could pen
V-ing form
I could be penning you could be penning she could be penning we could be penning you could be penning they could be penning
Perfect
I could have penned you could have penned she could have penned we could have penned you could have penned they could have penned
V-ing perfect
I could have been penning you could have been penning she could have been penning we could have been penning you could have been penning they could have been penning
Negation
Simple form
I could not pen you could not pen she could not pen we could not pen you could not pen they could not pen
V-ing form
I could not be penning you could not be penning she could not be penning we could not be penning you could not be penning they could not be penning
Perfect
I could not have penned you could not have penned she could not have penned we could not have penned you could not have penned they could not have penned
V-ing perfect
I could not have been penning you could not have been penning she could not have been penning we could not have been penning you could not have been penning they could not have been penning
Interrogative form
Simple form
could I pen? could you pen? could she pen? could we pen? could you pen? could they pen?
V-ing form
could I be penning? could you be penning? could she be penning? could we be penning? could you be penning? could they be penning?
Perfect
could I have penned? could you have penned? could she have penned? could we have penned? could you have penned? could they have penned?
V-ing perfect
could I have been penning? could you have been penning? could she have been penning? could we have been penning? could you have been penning? could they have been penning?
Interro-negative form
Simple form
could I not pen? could you not pen? could she not pen? could we not pen? could you not pen? could they not pen?
V-ing form
could I not be penning? could you not be penning? could she not be penning? could we not be penning? could you not be penning? could they not be penning?
Perfect
could I not have penned? could you not have penned? could she not have penned? could we not have penned? could you not have penned? could they not have penned?
V-ing perfect
could I not have been penning? could you not have been penning? could she not have been penning? could we not have been penning? could you not have been penning? could they not have been penning?