I could dock you could dock he could dock we could dock you could dock they could dock
V-ing form
I could be docking you could be docking he could be docking we could be docking you could be docking they could be docking
Perfect
I could have docked you could have docked he could have docked we could have docked you could have docked they could have docked
V-ing perfect
I could have been docking you could have been docking he could have been docking we could have been docking you could have been docking they could have been docking
Negation
Simple form
I couldn't dock you couldn't dock he couldn't dock we couldn't dock you couldn't dock they couldn't dock
V-ing form
I couldn't be docking you couldn't be docking he couldn't be docking we couldn't be docking you couldn't be docking they couldn't be docking
Perfect
I couldn't have docked you couldn't have docked he couldn't have docked we couldn't have docked you couldn't have docked they couldn't have docked
V-ing perfect
I couldn't have been docking you couldn't have been docking he couldn't have been docking we couldn't have been docking you couldn't have been docking they couldn't have been docking
Interrogative form
Simple form
could I dock? could you dock? could he dock? could we dock? could you dock? could they dock?
V-ing form
could I be docking? could you be docking? could he be docking? could we be docking? could you be docking? could they be docking?
Perfect
could I have docked? could you have docked? could he have docked? could we have docked? could you have docked? could they have docked?
V-ing perfect
could I have been docking? could you have been docking? could he have been docking? could we have been docking? could you have been docking? could they have been docking?
Interro-negative form
Simple form
couldn't I dock? couldn't you dock? couldn't he dock? couldn't we dock? couldn't you dock? couldn't they dock?
V-ing form
couldn't I be docking? couldn't you be docking? couldn't he be docking? couldn't we be docking? couldn't you be docking? couldn't they be docking?
Perfect
couldn't I have docked? couldn't you have docked? couldn't he have docked? couldn't we have docked? couldn't you have docked? couldn't they have docked?
V-ing perfect
couldn't I have been docking? couldn't you have been docking? couldn't he have been docking? couldn't we have been docking? couldn't you have been docking? couldn't they have been docking?