could whiten
Verbo regolare: whiten - whitened- whitened

Affermazione 	
Forma semplice 	Forma con V-ing 	Perfetto 	Perfetto con V-ing 	
I could whiten
you could whiten
he could whiten
we could whiten
you could whiten
they could whiten 	I could be whitening
you could be whitening
he could be whitening
we could be whitening
you could be whitening
they could be whitening	I could have whitened
you could have whitened
he could have whitened
we could have whitened
you could have whitened
they could have whitened	I could have been whitening
you could have been whitening
he could have been whitening
we could have been whitening
you could have been whitening
they could have been whitening	

Negazione 	
Forma semplice 	Forma con V-ing 	Perfetto 	Perfetto con V-ing 	
I couldn't whiten
you couldn't whiten
he couldn't whiten
we couldn't whiten
you couldn't whiten
they couldn't whiten 	I couldn't be whitening
you couldn't be whitening
he couldn't be whitening
we couldn't be whitening
you couldn't be whitening
they couldn't be whitening	I couldn't have whitened
you couldn't have whitened
he couldn't have whitened
we couldn't have whitened
you couldn't have whitened
they couldn't have whitened	I couldn't have been whitening
you couldn't have been whitening
he couldn't have been whitening
we couldn't have been whitening
you couldn't have been whitening
they couldn't have been whitening	

Forma interrogativa 	
Forma semplice 	Forma con V-ing 	Perfetto 	Perfetto con V-ing 	
could I whiten?
could you whiten?
could he whiten?
could we whiten?
could you whiten?
could they whiten? 	could I be whitening?
could you be whitening?
could he be whitening?
could we be whitening?
could you be whitening?
could they be whitening? 	could I have whitened?
could you have whitened?
could he have whitened?
could we have whitened?
could you have whitened?
could they have whitened? 	could I have been whitening?
could you have been whitening?
could he have been whitening?
could we have been whitening?
could you have been whitening?
could they have been whitening? 	

Forma interro-negativa 	
Forma semplice 	Forma con V-ing 	Perfetto 	Perfetto con V-ing 	
couldn't I whiten?
couldn't you whiten?
couldn't he whiten?
couldn't we whiten?
couldn't you whiten?
couldn't they whiten? 	couldn't I be whitening?
couldn't you be whitening?
couldn't he be whitening?
couldn't we be whitening?
couldn't you be whitening?
couldn't they be whitening? 	couldn't I have whitened?
couldn't you have whitened?
couldn't he have whitened?
couldn't we have whitened?
couldn't you have whitened?
couldn't they have whitened? 	couldn't I have been whitening?
couldn't you have been whitening?
couldn't he have been whitening?
couldn't we have been whitening?
couldn't you have been whitening?
couldn't they have been whitening?