I could skid you could skid she could skid we could skid you could skid they could skid
V-ing form
I could be skidding you could be skidding she could be skidding we could be skidding you could be skidding they could be skidding
Perfect
I could have skidded you could have skidded she could have skidded we could have skidded you could have skidded they could have skidded
V-ing perfect
I could have been skidding you could have been skidding she could have been skidding we could have been skidding you could have been skidding they could have been skidding
Negation
Simple form
I could not skid you could not skid she could not skid we could not skid you could not skid they could not skid
V-ing form
I could not be skidding you could not be skidding she could not be skidding we could not be skidding you could not be skidding they could not be skidding
Perfect
I could not have skidded you could not have skidded she could not have skidded we could not have skidded you could not have skidded they could not have skidded
V-ing perfect
I could not have been skidding you could not have been skidding she could not have been skidding we could not have been skidding you could not have been skidding they could not have been skidding
Interrogative form
Simple form
could I skid? could you skid? could she skid? could we skid? could you skid? could they skid?
V-ing form
could I be skidding? could you be skidding? could she be skidding? could we be skidding? could you be skidding? could they be skidding?
Perfect
could I have skidded? could you have skidded? could she have skidded? could we have skidded? could you have skidded? could they have skidded?
V-ing perfect
could I have been skidding? could you have been skidding? could she have been skidding? could we have been skidding? could you have been skidding? could they have been skidding?
Interro-negative form
Simple form
could I not skid? could you not skid? could she not skid? could we not skid? could you not skid? could they not skid?
V-ing form
could I not be skidding? could you not be skidding? could she not be skidding? could we not be skidding? could you not be skidding? could they not be skidding?
Perfect
could I not have skidded? could you not have skidded? could she not have skidded? could we not have skidded? could you not have skidded? could they not have skidded?
V-ing perfect
could I not have been skidding? could you not have been skidding? could she not have been skidding? could we not have been skidding? could you not have been skidding? could they not have been skidding?