could register
Verbo regular: register - registered- registered

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could register
you could register
he could register
we could register
you could register
they could register 	I could be registering
you could be registering
he could be registering
we could be registering
you could be registering
they could be registering	I could have registered
you could have registered
he could have registered
we could have registered
you could have registered
they could have registered	I could have been registering
you could have been registering
he could have been registering
we could have been registering
you could have been registering
they could have been registering	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I couldn't register
you couldn't register
he couldn't register
we couldn't register
you couldn't register
they couldn't register 	I couldn't be registering
you couldn't be registering
he couldn't be registering
we couldn't be registering
you couldn't be registering
they couldn't be registering	I couldn't have registered
you couldn't have registered
he couldn't have registered
we couldn't have registered
you couldn't have registered
they couldn't have registered	I couldn't have been registering
you couldn't have been registering
he couldn't have been registering
we couldn't have been registering
you couldn't have been registering
they couldn't have been registering	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I register?
could you register?
could he register?
could we register?
could you register?
could they register? 	could I be registering?
could you be registering?
could he be registering?
could we be registering?
could you be registering?
could they be registering? 	could I have registered?
could you have registered?
could he have registered?
could we have registered?
could you have registered?
could they have registered? 	could I have been registering?
could you have been registering?
could he have been registering?
could we have been registering?
could you have been registering?
could they have been registering? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
couldn't I register?
couldn't you register?
couldn't he register?
couldn't we register?
couldn't you register?
couldn't they register? 	couldn't I be registering?
couldn't you be registering?
couldn't he be registering?
couldn't we be registering?
couldn't you be registering?
couldn't they be registering? 	couldn't I have registered?
couldn't you have registered?
couldn't he have registered?
couldn't we have registered?
couldn't you have registered?
couldn't they have registered? 	couldn't I have been registering?
couldn't you have been registering?
couldn't he have been registering?
couldn't we have been registering?
couldn't you have been registering?
couldn't they have been registering?