I could moo you could moo she could moo we could moo you could moo they could moo
V-ing form
I could be mooing you could be mooing she could be mooing we could be mooing you could be mooing they could be mooing
Perfect
I could have mooed you could have mooed she could have mooed we could have mooed you could have mooed they could have mooed
V-ing perfect
I could have been mooing you could have been mooing she could have been mooing we could have been mooing you could have been mooing they could have been mooing
Negation
Simple form
I could not moo you could not moo she could not moo we could not moo you could not moo they could not moo
V-ing form
I could not be mooing you could not be mooing she could not be mooing we could not be mooing you could not be mooing they could not be mooing
Perfect
I could not have mooed you could not have mooed she could not have mooed we could not have mooed you could not have mooed they could not have mooed
V-ing perfect
I could not have been mooing you could not have been mooing she could not have been mooing we could not have been mooing you could not have been mooing they could not have been mooing
Interrogative form
Simple form
could I moo? could you moo? could she moo? could we moo? could you moo? could they moo?
V-ing form
could I be mooing? could you be mooing? could she be mooing? could we be mooing? could you be mooing? could they be mooing?
Perfect
could I have mooed? could you have mooed? could she have mooed? could we have mooed? could you have mooed? could they have mooed?
V-ing perfect
could I have been mooing? could you have been mooing? could she have been mooing? could we have been mooing? could you have been mooing? could they have been mooing?
Interro-negative form
Simple form
could I not moo? could you not moo? could she not moo? could we not moo? could you not moo? could they not moo?
V-ing form
could I not be mooing? could you not be mooing? could she not be mooing? could we not be mooing? could you not be mooing? could they not be mooing?
Perfect
could I not have mooed? could you not have mooed? could she not have mooed? could we not have mooed? could you not have mooed? could they not have mooed?
V-ing perfect
could I not have been mooing? could you not have been mooing? could she not have been mooing? could we not have been mooing? could you not have been mooing? could they not have been mooing?