could concenter
Verbo regular: concenter - concentered- concentered

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com 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	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could not concenter
you could not concenter
she 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
she could not be concentering
we could not be concentering
you could not be concentering
they could not be concentering	I could not have concentered
you could not have concentered
she 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
she could not have been concentering
we could not have been concentering
you could not have been concentering
they could not have been concentering	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com 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? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I not concenter?
could you not concenter?
could she 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 she not be concentering?
could we not be concentering?
could you not be concentering?
could they not be concentering? 	could I not have concentered?
could you not have concentered?
could she 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 she not have been concentering?
could we not have been concentering?
could you not have been concentering?
could they not have been concentering?