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 couldn't concert you couldn't concert he couldn't concert we couldn't concert you couldn't concert they couldn't concert	I couldn't be concerting you couldn't be concerting he couldn't be concerting we couldn't be concerting you couldn't be concerting they couldn't be concerting
Perfect	V-ing perfect
I couldn't have concerted you couldn't have concerted he couldn't have concerted we couldn't have concerted you couldn't have concerted they couldn't have concerted	I couldn't have been concerting you couldn't have been concerting he couldn't have been concerting we couldn't have been concerting you couldn't have been concerting they couldn't 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
couldn't I concert? couldn't you concert? couldn't he concert? couldn't we concert? couldn't you concert? couldn't they concert?	couldn't I be concerting? couldn't you be concerting? couldn't he be concerting? couldn't we be concerting? couldn't you be concerting? couldn't they be concerting?
Perfect	V-ing perfect
couldn't I have concerted? couldn't you have concerted? couldn't he have concerted? couldn't we have concerted? couldn't you have concerted? couldn't they have concerted?	couldn't I have been concerting? couldn't you have been concerting? couldn't he have been concerting? couldn't we have been concerting? couldn't you have been concerting? couldn't they have been concerting?