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