I could best you could best she could best we could best you could best they could best
V-ing form
I could be besting you could be besting she could be besting we could be besting you could be besting they could be besting
Perfect
I could have bested you could have bested she could have bested we could have bested you could have bested they could have bested
V-ing perfect
I could have been besting you could have been besting she could have been besting we could have been besting you could have been besting they could have been besting
Negation
Simple form
I could not best you could not best she could not best we could not best you could not best they could not best
V-ing form
I could not be besting you could not be besting she could not be besting we could not be besting you could not be besting they could not be besting
Perfect
I could not have bested you could not have bested she could not have bested we could not have bested you could not have bested they could not have bested
V-ing perfect
I could not have been besting you could not have been besting she could not have been besting we could not have been besting you could not have been besting they could not have been besting
Interrogative form
Simple form
could I best? could you best? could she best? could we best? could you best? could they best?
V-ing form
could I be besting? could you be besting? could she be besting? could we be besting? could you be besting? could they be besting?
Perfect
could I have bested? could you have bested? could she have bested? could we have bested? could you have bested? could they have bested?
V-ing perfect
could I have been besting? could you have been besting? could she have been besting? could we have been besting? could you have been besting? could they have been besting?
Interro-negative form
Simple form
could I not best? could you not best? could she not best? could we not best? could you not best? could they not best?
V-ing form
could I not be besting? could you not be besting? could she not be besting? could we not be besting? could you not be besting? could they not be besting?
Perfect
could I not have bested? could you not have bested? could she not have bested? could we not have bested? could you not have bested? could they not have bested?
V-ing perfect
could I not have been besting? could you not have been besting? could she not have been besting? could we not have been besting? could you not have been besting? could they not have been besting?