I could park you could park she could park we could park you could park they could park
V-ing form
I could be parking you could be parking she could be parking we could be parking you could be parking they could be parking
Perfect
I could have parked you could have parked she 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 she 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 she 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 she 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 she 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 she 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 she park? could we park? could you park? could they park?
V-ing form
could I be parking? could you be parking? could she be parking? could we be parking? could you be parking? could they be parking?
Perfect
could I have parked? could you have parked? could she 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 she 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 she 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 she 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 she 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 she have been parking? couldn't we have been parking? couldn't you have been parking? couldn't they have been parking?