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