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