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