could improve
Verbo regular: improve - improved- improved

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could improve
you could improve
he could improve
we could improve
you could improve
they could improve 	I could be improving
you could be improving
he could be improving
we could be improving
you could be improving
they could be improving	I could have improved
you could have improved
he could have improved
we could have improved
you could have improved
they could have improved	I could have been improving
you could have been improving
he could have been improving
we could have been improving
you could have been improving
they could have been improving	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could not improve
you could not improve
he could not improve
we could not improve
you could not improve
they could not improve 	I could not be improving
you could not be improving
he could not be improving
we could not be improving
you could not be improving
they could not be improving	I could not have improved
you could not have improved
he could not have improved
we could not have improved
you could not have improved
they could not have improved	I could not have been improving
you could not have been improving
he could not have been improving
we could not have been improving
you could not have been improving
they could not have been improving	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I improve?
could you improve?
could he improve?
could we improve?
could you improve?
could they improve? 	could I be improving?
could you be improving?
could he be improving?
could we be improving?
could you be improving?
could they be improving? 	could I have improved?
could you have improved?
could he have improved?
could we have improved?
could you have improved?
could they have improved? 	could I have been improving?
could you have been improving?
could he have been improving?
could we have been improving?
could you have been improving?
could they have been improving? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I not improve?
could you not improve?
could he not improve?
could we not improve?
could you not improve?
could they not improve? 	could I not be improving?
could you not be improving?
could he not be improving?
could we not be improving?
could you not be improving?
could they not be improving? 	could I not have improved?
could you not have improved?
could he not have improved?
could we not have improved?
could you not have improved?
could they not have improved? 	could I not have been improving?
could you not have been improving?
could he not have been improving?
could we not have been improving?
could you not have been improving?
could they not have been improving?