I could taper you could taper she could taper we could taper you could taper they could taper
V-ing form
I could be tapering you could be tapering she could be tapering we could be tapering you could be tapering they could be tapering
Perfect
I could have tapered you could have tapered she could have tapered we could have tapered you could have tapered they could have tapered
V-ing perfect
I could have been tapering you could have been tapering she could have been tapering we could have been tapering you could have been tapering they could have been tapering
Negation
Simple form
I couldn't taper you couldn't taper she couldn't taper we couldn't taper you couldn't taper they couldn't taper
V-ing form
I couldn't be tapering you couldn't be tapering she couldn't be tapering we couldn't be tapering you couldn't be tapering they couldn't be tapering
Perfect
I couldn't have tapered you couldn't have tapered she couldn't have tapered we couldn't have tapered you couldn't have tapered they couldn't have tapered
V-ing perfect
I couldn't have been tapering you couldn't have been tapering she couldn't have been tapering we couldn't have been tapering you couldn't have been tapering they couldn't have been tapering
Interrogative form
Simple form
could I taper? could you taper? could she taper? could we taper? could you taper? could they taper?
V-ing form
could I be tapering? could you be tapering? could she be tapering? could we be tapering? could you be tapering? could they be tapering?
Perfect
could I have tapered? could you have tapered? could she have tapered? could we have tapered? could you have tapered? could they have tapered?
V-ing perfect
could I have been tapering? could you have been tapering? could she have been tapering? could we have been tapering? could you have been tapering? could they have been tapering?
Interro-negative form
Simple form
couldn't I taper? couldn't you taper? couldn't she taper? couldn't we taper? couldn't you taper? couldn't they taper?
V-ing form
couldn't I be tapering? couldn't you be tapering? couldn't she be tapering? couldn't we be tapering? couldn't you be tapering? couldn't they be tapering?
Perfect
couldn't I have tapered? couldn't you have tapered? couldn't she have tapered? couldn't we have tapered? couldn't you have tapered? couldn't they have tapered?
V-ing perfect
couldn't I have been tapering? couldn't you have been tapering? couldn't she have been tapering? couldn't we have been tapering? couldn't you have been tapering? couldn't they have been tapering?