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