I could protest you could protest she could protest we could protest you could protest they could protest
V-ing form
I could be protesting you could be protesting she could be protesting we could be protesting you could be protesting they could be protesting
Perfect
I could have protested you could have protested she could have protested we could have protested you could have protested they could have protested
V-ing perfect
I could have been protesting you could have been protesting she could have been protesting we could have been protesting you could have been protesting they could have been protesting
Negation
Simple form
I could not protest you could not protest she could not protest we could not protest you could not protest they could not protest
V-ing form
I could not be protesting you could not be protesting she could not be protesting we could not be protesting you could not be protesting they could not be protesting
Perfect
I could not have protested you could not have protested she could not have protested we could not have protested you could not have protested they could not have protested
V-ing perfect
I could not have been protesting you could not have been protesting she could not have been protesting we could not have been protesting you could not have been protesting they could not have been protesting
Interrogative form
Simple form
could I protest? could you protest? could she protest? could we protest? could you protest? could they protest?
V-ing form
could I be protesting? could you be protesting? could she be protesting? could we be protesting? could you be protesting? could they be protesting?
Perfect
could I have protested? could you have protested? could she have protested? could we have protested? could you have protested? could they have protested?
V-ing perfect
could I have been protesting? could you have been protesting? could she have been protesting? could we have been protesting? could you have been protesting? could they have been protesting?
Interro-negative form
Simple form
could I not protest? could you not protest? could she not protest? could we not protest? could you not protest? could they not protest?
V-ing form
could I not be protesting? could you not be protesting? could she not be protesting? could we not be protesting? could you not be protesting? could they not be protesting?
Perfect
could I not have protested? could you not have protested? could she not have protested? could we not have protested? could you not have protested? could they not have protested?
V-ing perfect
could I not have been protesting? could you not have been protesting? could she not have been protesting? could we not have been protesting? could you not have been protesting? could they not have been protesting?