English verb conjugation
COULD CONCENTER

Regular verb: concenter - concentered - concentered

Affirmation

Simple form	V-ing form
I could concenter you could concenter he could concenter we could concenter you could concenter they could concenter	I could be concentering you could be concentering he could be concentering we could be concentering you could be concentering they could be concentering
Perfect	V-ing perfect
I could have concentered you could have concentered he could have concentered we could have concentered you could have concentered they could have concentered	I could have been concentering you could have been concentering he could have been concentering we could have been concentering you could have been concentering they could have been concentering

Negation

Simple form	V-ing form
I could not concenter you could not concenter he could not concenter we could not concenter you could not concenter they could not concenter	I could not be concentering you could not be concentering he could not be concentering we could not be concentering you could not be concentering they could not be concentering
Perfect	V-ing perfect
I could not have concentered you could not have concentered he could not have concentered we could not have concentered you could not have concentered they could not have concentered	I could not have been concentering you could not have been concentering he could not have been concentering we could not have been concentering you could not have been concentering they could not have been concentering

Interrogative form

Simple form	V-ing form
could I concenter? could you concenter? could he concenter? could we concenter? could you concenter? could they concenter?	could I be concentering? could you be concentering? could he be concentering? could we be concentering? could you be concentering? could they be concentering?
Perfect	V-ing perfect
could I have concentered? could you have concentered? could he have concentered? could we have concentered? could you have concentered? could they have concentered?	could I have been concentering? could you have been concentering? could he have been concentering? could we have been concentering? could you have been concentering? could they have been concentering?

Interro-negative form

Simple form	V-ing form
could I not concenter? could you not concenter? could he not concenter? could we not concenter? could you not concenter? could they not concenter?	could I not be concentering? could you not be concentering? could he not be concentering? could we not be concentering? could you not be concentering? could they not be concentering?
Perfect	V-ing perfect
could I not have concentered? could you not have concentered? could he not have concentered? could we not have concentered? could you not have concentered? could they not have concentered?	could I not have been concentering? could you not have been concentering? could he not have been concentering? could we not have been concentering? could you not have been concentering? could they not have been concentering?