I could run you could run he could run we could run you could run they could run
V-ing form
I could be running you could be running he could be running we could be running you could be running they could be running
Perfect
I could have run you could have run he could have run we could have run you could have run they could have run
V-ing perfect
I could have been running you could have been running he could have been running we could have been running you could have been running they could have been running
Negation
Simple form
I could not run you could not run he could not run we could not run you could not run they could not run
V-ing form
I could not be running you could not be running he could not be running we could not be running you could not be running they could not be running
Perfect
I could not have run you could not have run he could not have run we could not have run you could not have run they could not have run
V-ing perfect
I could not have been running you could not have been running he could not have been running we could not have been running you could not have been running they could not have been running
Interrogative form
Simple form
could I run? could you run? could he run? could we run? could you run? could they run?
V-ing form
could I be running? could you be running? could he be running? could we be running? could you be running? could they be running?
Perfect
could I have run? could you have run? could he have run? could we have run? could you have run? could they have run?
V-ing perfect
could I have been running? could you have been running? could he have been running? could we have been running? could you have been running? could they have been running?
Interro-negative form
Simple form
could I not run? could you not run? could he not run? could we not run? could you not run? could they not run?
V-ing form
could I not be running? could you not be running? could he not be running? could we not be running? could you not be running? could they not be running?
Perfect
could I not have run? could you not have run? could he not have run? could we not have run? could you not have run? could they not have run?
V-ing perfect
could I not have been running? could you not have been running? could he not have been running? could we not have been running? could you not have been running? could they not have been running?