could concenter
Verbe régulier : concenter - concentered- concentered

Affirmation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I could concenter
you could concenter
she could concenter
we could concenter
you could concenter
they could concenter 	I could be concentering
you could be concentering
she could be concentering
we could be concentering
you could be concentering
they could be concentering	I could have concentered
you could have concentered
she 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
she could have been concentering
we could have been concentering
you could have been concentering
they could have been concentering	

Négation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I couldn't concenter
you couldn't concenter
she couldn't concenter
we couldn't concenter
you couldn't concenter
they couldn't concenter 	I couldn't be concentering
you couldn't be concentering
she couldn't be concentering
we couldn't be concentering
you couldn't be concentering
they couldn't be concentering	I couldn't have concentered
you couldn't have concentered
she couldn't have concentered
we couldn't have concentered
you couldn't have concentered
they couldn't have concentered	I couldn't have been concentering
you couldn't have been concentering
she couldn't have been concentering
we couldn't have been concentering
you couldn't have been concentering
they couldn't have been concentering	

Forme interrogative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
could I concenter?
could you concenter?
could she concenter?
could we concenter?
could you concenter?
could they concenter? 	could I be concentering?
could you be concentering?
could she be concentering?
could we be concentering?
could you be concentering?
could they be concentering? 	could I have concentered?
could you have concentered?
could she 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 she have been concentering?
could we have been concentering?
could you have been concentering?
could they have been concentering? 	

Forme interro-négative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
couldn't I concenter?
couldn't you concenter?
couldn't she concenter?
couldn't we concenter?
couldn't you concenter?
couldn't they concenter? 	couldn't I be concentering?
couldn't you be concentering?
couldn't she be concentering?
couldn't we be concentering?
couldn't you be concentering?
couldn't they be concentering? 	couldn't I have concentered?
couldn't you have concentered?
couldn't she have concentered?
couldn't we have concentered?
couldn't you have concentered?
couldn't they have concentered? 	couldn't I have been concentering?
couldn't you have been concentering?
couldn't she have been concentering?
couldn't we have been concentering?
couldn't you have been concentering?
couldn't they have been concentering?