must ruff
Verbo regular: ruff - ruffed- ruffed

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must ruff
you must ruff
he must ruff
we must ruff
you must ruff
they must ruff 	I must be ruffing
you must be ruffing
he must be ruffing
we must be ruffing
you must be ruffing
they must be ruffing	I must have ruffed
you must have ruffed
he must have ruffed
we must have ruffed
you must have ruffed
they must have ruffed	I must have been ruffing
you must have been ruffing
he must have been ruffing
we must have been ruffing
you must have been ruffing
they must have been ruffing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I mustn't ruff
you mustn't ruff
he mustn't ruff
we mustn't ruff
you mustn't ruff
they mustn't ruff 	I mustn't be ruffing
you mustn't be ruffing
he mustn't be ruffing
we mustn't be ruffing
you mustn't be ruffing
they mustn't be ruffing	I mustn't have ruffed
you mustn't have ruffed
he mustn't have ruffed
we mustn't have ruffed
you mustn't have ruffed
they mustn't have ruffed	I mustn't have been ruffing
you mustn't have been ruffing
he mustn't have been ruffing
we mustn't have been ruffing
you mustn't have been ruffing
they mustn't have been ruffing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I ruff?
must you ruff?
must he ruff?
must we ruff?
must you ruff?
must they ruff? 	must I be ruffing?
must you be ruffing?
must he be ruffing?
must we be ruffing?
must you be ruffing?
must they be ruffing? 	must I have ruffed?
must you have ruffed?
must he have ruffed?
must we have ruffed?
must you have ruffed?
must they have ruffed? 	must I have been ruffing?
must you have been ruffing?
must he have been ruffing?
must we have been ruffing?
must you have been ruffing?
must they have been ruffing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
mustn't I ruff?
mustn't you ruff?
mustn't he ruff?
mustn't we ruff?
mustn't you ruff?
mustn't they ruff? 	mustn't I be ruffing?
mustn't you be ruffing?
mustn't he be ruffing?
mustn't we be ruffing?
mustn't you be ruffing?
mustn't they be ruffing? 	mustn't I have ruffed?
mustn't you have ruffed?
mustn't he have ruffed?
mustn't we have ruffed?
mustn't you have ruffed?
mustn't they have ruffed? 	mustn't I have been ruffing?
mustn't you have been ruffing?
mustn't he have been ruffing?
mustn't we have been ruffing?
mustn't you have been ruffing?
mustn't they have been ruffing?