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