I could help you could help she could help we could help you could help they could help
V-ing form
I could be helping you could be helping she could be helping we could be helping you could be helping they could be helping
Perfect
I could have helped you could have helped she could have helped we could have helped you could have helped they could have helped
V-ing perfect
I could have been helping you could have been helping she could have been helping we could have been helping you could have been helping they could have been helping
Negation
Simple form
I could not help you could not help she could not help we could not help you could not help they could not help
V-ing form
I could not be helping you could not be helping she could not be helping we could not be helping you could not be helping they could not be helping
Perfect
I could not have helped you could not have helped she could not have helped we could not have helped you could not have helped they could not have helped
V-ing perfect
I could not have been helping you could not have been helping she could not have been helping we could not have been helping you could not have been helping they could not have been helping
Interrogative form
Simple form
could I help? could you help? could she help? could we help? could you help? could they help?
V-ing form
could I be helping? could you be helping? could she be helping? could we be helping? could you be helping? could they be helping?
Perfect
could I have helped? could you have helped? could she have helped? could we have helped? could you have helped? could they have helped?
V-ing perfect
could I have been helping? could you have been helping? could she have been helping? could we have been helping? could you have been helping? could they have been helping?
Interro-negative form
Simple form
could I not help? could you not help? could she not help? could we not help? could you not help? could they not help?
V-ing form
could I not be helping? could you not be helping? could she not be helping? could we not be helping? could you not be helping? could they not be helping?
Perfect
could I not have helped? could you not have helped? could she not have helped? could we not have helped? could you not have helped? could they not have helped?
V-ing perfect
could I not have been helping? could you not have been helping? could she not have been helping? could we not have been helping? could you not have been helping? could they not have been helping?