must stiffen
Verbo regolare: stiffen - stiffened- stiffened

Affermazione 	
Forma semplice 	Forma con V-ing 	Perfetto 	Perfetto con V-ing 	
I must stiffen
you must stiffen
he must stiffen
we must stiffen
you must stiffen
they must stiffen 	I must be stiffening
you must be stiffening
he must be stiffening
we must be stiffening
you must be stiffening
they must be stiffening	I must have stiffened
you must have stiffened
he must have stiffened
we must have stiffened
you must have stiffened
they must have stiffened	I must have been stiffening
you must have been stiffening
he must have been stiffening
we must have been stiffening
you must have been stiffening
they must have been stiffening	

Negazione 	
Forma semplice 	Forma con V-ing 	Perfetto 	Perfetto con V-ing 	
I mustn't stiffen
you mustn't stiffen
he mustn't stiffen
we mustn't stiffen
you mustn't stiffen
they mustn't stiffen 	I mustn't be stiffening
you mustn't be stiffening
he mustn't be stiffening
we mustn't be stiffening
you mustn't be stiffening
they mustn't be stiffening	I mustn't have stiffened
you mustn't have stiffened
he mustn't have stiffened
we mustn't have stiffened
you mustn't have stiffened
they mustn't have stiffened	I mustn't have been stiffening
you mustn't have been stiffening
he mustn't have been stiffening
we mustn't have been stiffening
you mustn't have been stiffening
they mustn't have been stiffening	

Forma interrogativa 	
Forma semplice 	Forma con V-ing 	Perfetto 	Perfetto con V-ing 	
must I stiffen?
must you stiffen?
must he stiffen?
must we stiffen?
must you stiffen?
must they stiffen? 	must I be stiffening?
must you be stiffening?
must he be stiffening?
must we be stiffening?
must you be stiffening?
must they be stiffening? 	must I have stiffened?
must you have stiffened?
must he have stiffened?
must we have stiffened?
must you have stiffened?
must they have stiffened? 	must I have been stiffening?
must you have been stiffening?
must he have been stiffening?
must we have been stiffening?
must you have been stiffening?
must they have been stiffening? 	

Forma interro-negativa 	
Forma semplice 	Forma con V-ing 	Perfetto 	Perfetto con V-ing 	
mustn't I stiffen?
mustn't you stiffen?
mustn't he stiffen?
mustn't we stiffen?
mustn't you stiffen?
mustn't they stiffen? 	mustn't I be stiffening?
mustn't you be stiffening?
mustn't he be stiffening?
mustn't we be stiffening?
mustn't you be stiffening?
mustn't they be stiffening? 	mustn't I have stiffened?
mustn't you have stiffened?
mustn't he have stiffened?
mustn't we have stiffened?
mustn't you have stiffened?
mustn't they have stiffened? 	mustn't I have been stiffening?
mustn't you have been stiffening?
mustn't he have been stiffening?
mustn't we have been stiffening?
mustn't you have been stiffening?
mustn't they have been stiffening?