I could gabble you could gabble he could gabble we could gabble you could gabble they could gabble
V-ing form
I could be gabbling you could be gabbling he could be gabbling we could be gabbling you could be gabbling they could be gabbling
Perfect
I could have gabbled you could have gabbled he could have gabbled we could have gabbled you could have gabbled they could have gabbled
V-ing perfect
I could have been gabbling you could have been gabbling he could have been gabbling we could have been gabbling you could have been gabbling they could have been gabbling
Negation
Simple form
I could not gabble you could not gabble he could not gabble we could not gabble you could not gabble they could not gabble
V-ing form
I could not be gabbling you could not be gabbling he could not be gabbling we could not be gabbling you could not be gabbling they could not be gabbling
Perfect
I could not have gabbled you could not have gabbled he could not have gabbled we could not have gabbled you could not have gabbled they could not have gabbled
V-ing perfect
I could not have been gabbling you could not have been gabbling he could not have been gabbling we could not have been gabbling you could not have been gabbling they could not have been gabbling
Interrogative form
Simple form
could I gabble? could you gabble? could he gabble? could we gabble? could you gabble? could they gabble?
V-ing form
could I be gabbling? could you be gabbling? could he be gabbling? could we be gabbling? could you be gabbling? could they be gabbling?
Perfect
could I have gabbled? could you have gabbled? could he have gabbled? could we have gabbled? could you have gabbled? could they have gabbled?
V-ing perfect
could I have been gabbling? could you have been gabbling? could he have been gabbling? could we have been gabbling? could you have been gabbling? could they have been gabbling?
Interro-negative form
Simple form
could I not gabble? could you not gabble? could he not gabble? could we not gabble? could you not gabble? could they not gabble?
V-ing form
could I not be gabbling? could you not be gabbling? could he not be gabbling? could we not be gabbling? could you not be gabbling? could they not be gabbling?
Perfect
could I not have gabbled? could you not have gabbled? could he not have gabbled? could we not have gabbled? could you not have gabbled? could they not have gabbled?
V-ing perfect
could I not have been gabbling? could you not have been gabbling? could he not have been gabbling? could we not have been gabbling? could you not have been gabbling? could they not have been gabbling?