I could concretize you could concretize he could concretize we could concretize you could concretize they could concretize
V-ing form
I could be concretizing you could be concretizing he could be concretizing we could be concretizing you could be concretizing they could be concretizing
Perfect
I could have concretized you could have concretized he could have concretized we could have concretized you could have concretized they could have concretized
V-ing perfect
I could have been concretizing you could have been concretizing he could have been concretizing we could have been concretizing you could have been concretizing they could have been concretizing
Negation
Simple form
I could not concretize you could not concretize he could not concretize we could not concretize you could not concretize they could not concretize
V-ing form
I could not be concretizing you could not be concretizing he could not be concretizing we could not be concretizing you could not be concretizing they could not be concretizing
Perfect
I could not have concretized you could not have concretized he could not have concretized we could not have concretized you could not have concretized they could not have concretized
V-ing perfect
I could not have been concretizing you could not have been concretizing he could not have been concretizing we could not have been concretizing you could not have been concretizing they could not have been concretizing
Interrogative form
Simple form
could I concretize? could you concretize? could he concretize? could we concretize? could you concretize? could they concretize?
V-ing form
could I be concretizing? could you be concretizing? could he be concretizing? could we be concretizing? could you be concretizing? could they be concretizing?
Perfect
could I have concretized? could you have concretized? could he have concretized? could we have concretized? could you have concretized? could they have concretized?
V-ing perfect
could I have been concretizing? could you have been concretizing? could he have been concretizing? could we have been concretizing? could you have been concretizing? could they have been concretizing?
Interro-negative form
Simple form
could I not concretize? could you not concretize? could he not concretize? could we not concretize? could you not concretize? could they not concretize?
V-ing form
could I not be concretizing? could you not be concretizing? could he not be concretizing? could we not be concretizing? could you not be concretizing? could they not be concretizing?
Perfect
could I not have concretized? could you not have concretized? could he not have concretized? could we not have concretized? could you not have concretized? could they not have concretized?
V-ing perfect
could I not have been concretizing? could you not have been concretizing? could he not have been concretizing? could we not have been concretizing? could you not have been concretizing? could they not have been concretizing?