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