I could coo you could coo she could coo we could coo you could coo they could coo
V-ing form
I could be cooing you could be cooing she could be cooing we could be cooing you could be cooing they could be cooing
Perfect
I could have cooed you could have cooed she could have cooed we could have cooed you could have cooed they could have cooed
V-ing perfect
I could have been cooing you could have been cooing she could have been cooing we could have been cooing you could have been cooing they could have been cooing
Negation
Simple form
I couldn't coo you couldn't coo she couldn't coo we couldn't coo you couldn't coo they couldn't coo
V-ing form
I couldn't be cooing you couldn't be cooing she couldn't be cooing we couldn't be cooing you couldn't be cooing they couldn't be cooing
Perfect
I couldn't have cooed you couldn't have cooed she couldn't have cooed we couldn't have cooed you couldn't have cooed they couldn't have cooed
V-ing perfect
I couldn't have been cooing you couldn't have been cooing she couldn't have been cooing we couldn't have been cooing you couldn't have been cooing they couldn't have been cooing
Interrogative form
Simple form
could I coo? could you coo? could she coo? could we coo? could you coo? could they coo?
V-ing form
could I be cooing? could you be cooing? could she be cooing? could we be cooing? could you be cooing? could they be cooing?
Perfect
could I have cooed? could you have cooed? could she have cooed? could we have cooed? could you have cooed? could they have cooed?
V-ing perfect
could I have been cooing? could you have been cooing? could she have been cooing? could we have been cooing? could you have been cooing? could they have been cooing?
Interro-negative form
Simple form
couldn't I coo? couldn't you coo? couldn't she coo? couldn't we coo? couldn't you coo? couldn't they coo?
V-ing form
couldn't I be cooing? couldn't you be cooing? couldn't she be cooing? couldn't we be cooing? couldn't you be cooing? couldn't they be cooing?
Perfect
couldn't I have cooed? couldn't you have cooed? couldn't she have cooed? couldn't we have cooed? couldn't you have cooed? couldn't they have cooed?
V-ing perfect
couldn't I have been cooing? couldn't you have been cooing? couldn't she have been cooing? couldn't we have been cooing? couldn't you have been cooing? couldn't they have been cooing?