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 couldn't gabble you couldn't gabble he couldn't gabble we couldn't gabble you couldn't gabble they couldn't gabble
V-ing form
I couldn't be gabbling you couldn't be gabbling he couldn't be gabbling we couldn't be gabbling you couldn't be gabbling they couldn't be gabbling
Perfect
I couldn't have gabbled you couldn't have gabbled he couldn't have gabbled we couldn't have gabbled you couldn't have gabbled they couldn't have gabbled
V-ing perfect
I couldn't have been gabbling you couldn't have been gabbling he couldn't have been gabbling we couldn't have been gabbling you couldn't have been gabbling they couldn't 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
couldn't I gabble? couldn't you gabble? couldn't he gabble? couldn't we gabble? couldn't you gabble? couldn't they gabble?
V-ing form
couldn't I be gabbling? couldn't you be gabbling? couldn't he be gabbling? couldn't we be gabbling? couldn't you be gabbling? couldn't they be gabbling?
Perfect
couldn't I have gabbled? couldn't you have gabbled? couldn't he have gabbled? couldn't we have gabbled? couldn't you have gabbled? couldn't they have gabbled?
V-ing perfect
couldn't I have been gabbling? couldn't you have been gabbling? couldn't he have been gabbling? couldn't we have been gabbling? couldn't you have been gabbling? couldn't they have been gabbling?