could dull
Verbo regular: dull - dulled- dulled

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could dull
you could dull
he could dull
we could dull
you could dull
they could dull 	I could be dulling
you could be dulling
he could be dulling
we could be dulling
you could be dulling
they could be dulling	I could have dulled
you could have dulled
he could have dulled
we could have dulled
you could have dulled
they could have dulled	I could have been dulling
you could have been dulling
he could have been dulling
we could have been dulling
you could have been dulling
they could have been dulling	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I couldn't dull
you couldn't dull
he couldn't dull
we couldn't dull
you couldn't dull
they couldn't dull 	I couldn't be dulling
you couldn't be dulling
he couldn't be dulling
we couldn't be dulling
you couldn't be dulling
they couldn't be dulling	I couldn't have dulled
you couldn't have dulled
he couldn't have dulled
we couldn't have dulled
you couldn't have dulled
they couldn't have dulled	I couldn't have been dulling
you couldn't have been dulling
he couldn't have been dulling
we couldn't have been dulling
you couldn't have been dulling
they couldn't have been dulling	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I dull?
could you dull?
could he dull?
could we dull?
could you dull?
could they dull? 	could I be dulling?
could you be dulling?
could he be dulling?
could we be dulling?
could you be dulling?
could they be dulling? 	could I have dulled?
could you have dulled?
could he have dulled?
could we have dulled?
could you have dulled?
could they have dulled? 	could I have been dulling?
could you have been dulling?
could he have been dulling?
could we have been dulling?
could you have been dulling?
could they have been dulling? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
couldn't I dull?
couldn't you dull?
couldn't he dull?
couldn't we dull?
couldn't you dull?
couldn't they dull? 	couldn't I be dulling?
couldn't you be dulling?
couldn't he be dulling?
couldn't we be dulling?
couldn't you be dulling?
couldn't they be dulling? 	couldn't I have dulled?
couldn't you have dulled?
couldn't he have dulled?
couldn't we have dulled?
couldn't you have dulled?
couldn't they have dulled? 	couldn't I have been dulling?
couldn't you have been dulling?
couldn't he have been dulling?
couldn't we have been dulling?
couldn't you have been dulling?
couldn't they have been dulling?