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 couldn't moo you couldn't moo she couldn't moo we couldn't moo you couldn't moo they couldn't moo
V-ing form
I couldn't be mooing you couldn't be mooing she couldn't be mooing we couldn't be mooing you couldn't be mooing they couldn't be mooing
Perfect
I couldn't have mooed you couldn't have mooed she couldn't have mooed we couldn't have mooed you couldn't have mooed they couldn't have mooed
V-ing perfect
I couldn't have been mooing you couldn't have been mooing she couldn't have been mooing we couldn't have been mooing you couldn't have been mooing they couldn't 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
couldn't I moo? couldn't you moo? couldn't she moo? couldn't we moo? couldn't you moo? couldn't they moo?
V-ing form
couldn't I be mooing? couldn't you be mooing? couldn't she be mooing? couldn't we be mooing? couldn't you be mooing? couldn't they be mooing?
Perfect
couldn't I have mooed? couldn't you have mooed? couldn't she have mooed? couldn't we have mooed? couldn't you have mooed? couldn't they have mooed?
V-ing perfect
couldn't I have been mooing? couldn't you have been mooing? couldn't she have been mooing? couldn't we have been mooing? couldn't you have been mooing? couldn't they have been mooing?