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