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 couldn't run you couldn't run he couldn't run we couldn't run you couldn't run they couldn't run
V-ing form
I couldn't be running you couldn't be running he couldn't be running we couldn't be running you couldn't be running they couldn't be running
Perfect
I couldn't have run you couldn't have run he couldn't have run we couldn't have run you couldn't have run they couldn't have run
V-ing perfect
I couldn't have been running you couldn't have been running he couldn't have been running we couldn't have been running you couldn't have been running they couldn't 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
couldn't I run? couldn't you run? couldn't he run? couldn't we run? couldn't you run? couldn't they run?
V-ing form
couldn't I be running? couldn't you be running? couldn't he be running? couldn't we be running? couldn't you be running? couldn't they be running?
Perfect
couldn't I have run? couldn't you have run? couldn't he have run? couldn't we have run? couldn't you have run? couldn't they have run?
V-ing perfect
couldn't I have been running? couldn't you have been running? couldn't he have been running? couldn't we have been running? couldn't you have been running? couldn't they have been running?