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 couldn't help you couldn't help she couldn't help we couldn't help you couldn't help they couldn't help
V-ing form
I couldn't be helping you couldn't be helping she couldn't be helping we couldn't be helping you couldn't be helping they couldn't be helping
Perfect
I couldn't have helped you couldn't have helped she couldn't have helped we couldn't have helped you couldn't have helped they couldn't have helped
V-ing perfect
I couldn't have been helping you couldn't have been helping she couldn't have been helping we couldn't have been helping you couldn't have been helping they couldn't 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
couldn't I help? couldn't you help? couldn't she help? couldn't we help? couldn't you help? couldn't they help?
V-ing form
couldn't I be helping? couldn't you be helping? couldn't she be helping? couldn't we be helping? couldn't you be helping? couldn't they be helping?
Perfect
couldn't I have helped? couldn't you have helped? couldn't she have helped? couldn't we have helped? couldn't you have helped? couldn't they have helped?
V-ing perfect
couldn't I have been helping? couldn't you have been helping? couldn't she have been helping? couldn't we have been helping? couldn't you have been helping? couldn't they have been helping?