I could taper you could taper he could taper we could taper you could taper they could taper
V-ing form
I could be tapering you could be tapering he could be tapering we could be tapering you could be tapering they could be tapering
Perfect
I could have tapered you could have tapered he 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 he could have been tapering we could have been tapering you could have been tapering they could have been tapering
Negation
Simple form
I could not taper you could not taper he could not taper we could not taper you could not taper they could not taper
V-ing form
I could not be tapering you could not be tapering he could not be tapering we could not be tapering you could not be tapering they could not be tapering
Perfect
I could not have tapered you could not have tapered he could not have tapered we could not have tapered you could not have tapered they could not have tapered
V-ing perfect
I could not have been tapering you could not have been tapering he could not have been tapering we could not have been tapering you could not have been tapering they could not have been tapering
Interrogative form
Simple form
could I taper? could you taper? could he taper? could we taper? could you taper? could they taper?
V-ing form
could I be tapering? could you be tapering? could he be tapering? could we be tapering? could you be tapering? could they be tapering?
Perfect
could I have tapered? could you have tapered? could he 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 he have been tapering? could we have been tapering? could you have been tapering? could they have been tapering?
Interro-negative form
Simple form
could I not taper? could you not taper? could he not taper? could we not taper? could you not taper? could they not taper?
V-ing form
could I not be tapering? could you not be tapering? could he not be tapering? could we not be tapering? could you not be tapering? could they not be tapering?
Perfect
could I not have tapered? could you not have tapered? could he not have tapered? could we not have tapered? could you not have tapered? could they not have tapered?
V-ing perfect
could I not have been tapering? could you not have been tapering? could he not have been tapering? could we not have been tapering? could you not have been tapering? could they not have been tapering?