English verb conjugation
COULD CONCERT

Regular verb: concert - concerted - concerted

Affirmation

Simple form	V-ing form
I could concert you could concert he could concert we could concert you could concert they could concert	I could be concerting you could be concerting he could be concerting we could be concerting you could be concerting they could be concerting
Perfect	V-ing perfect
I could have concerted you could have concerted he could have concerted we could have concerted you could have concerted they could have concerted	I could have been concerting you could have been concerting he could have been concerting we could have been concerting you could have been concerting they could have been concerting

Negation

Simple form	V-ing form
I could not concert you could not concert he could not concert we could not concert you could not concert they could not concert	I could not be concerting you could not be concerting he could not be concerting we could not be concerting you could not be concerting they could not be concerting
Perfect	V-ing perfect
I could not have concerted you could not have concerted he could not have concerted we could not have concerted you could not have concerted they could not have concerted	I could not have been concerting you could not have been concerting he could not have been concerting we could not have been concerting you could not have been concerting they could not have been concerting

Interrogative form

Simple form	V-ing form
could I concert? could you concert? could he concert? could we concert? could you concert? could they concert?	could I be concerting? could you be concerting? could he be concerting? could we be concerting? could you be concerting? could they be concerting?
Perfect	V-ing perfect
could I have concerted? could you have concerted? could he have concerted? could we have concerted? could you have concerted? could they have concerted?	could I have been concerting? could you have been concerting? could he have been concerting? could we have been concerting? could you have been concerting? could they have been concerting?

Interro-negative form

Simple form	V-ing form
could I not concert? could you not concert? could he not concert? could we not concert? could you not concert? could they not concert?	could I not be concerting? could you not be concerting? could he not be concerting? could we not be concerting? could you not be concerting? could they not be concerting?
Perfect	V-ing perfect
could I not have concerted? could you not have concerted? could he not have concerted? could we not have concerted? could you not have concerted? could they not have concerted?	could I not have been concerting? could you not have been concerting? could he not have been concerting? could we not have been concerting? could you not have been concerting? could they not have been concerting?