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