may stiffen
Verbo regular: stiffen - stiffened- stiffened

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I may stiffen
you may stiffen
he may stiffen
we may stiffen
you may stiffen
they may stiffen 	I may be stiffening
you may be stiffening
he may be stiffening
we may be stiffening
you may be stiffening
they may be stiffening	I may have stiffened
you may have stiffened
he may have stiffened
we may have stiffened
you may have stiffened
they may have stiffened	I may have been stiffening
you may have been stiffening
he may have been stiffening
we may have been stiffening
you may have been stiffening
they may have been stiffening	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I may not stiffen
you may not stiffen
he may not stiffen
we may not stiffen
you may not stiffen
they may not stiffen 	I may not be stiffening
you may not be stiffening
he may not be stiffening
we may not be stiffening
you may not be stiffening
they may not be stiffening	I may not have stiffened
you may not have stiffened
he may not have stiffened
we may not have stiffened
you may not have stiffened
they may not have stiffened	I may not have been stiffening
you may not have been stiffening
he may not have been stiffening
we may not have been stiffening
you may not have been stiffening
they may not have been stiffening	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
may I stiffen?
may you stiffen?
may he stiffen?
may we stiffen?
may you stiffen?
may they stiffen? 	may I be stiffening?
may you be stiffening?
may he be stiffening?
may we be stiffening?
may you be stiffening?
may they be stiffening? 	may I have stiffened?
may you have stiffened?
may he have stiffened?
may we have stiffened?
may you have stiffened?
may they have stiffened? 	may I have been stiffening?
may you have been stiffening?
may he have been stiffening?
may we have been stiffening?
may you have been stiffening?
may they have been stiffening? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
may I not stiffen?
may you not stiffen?
may he not stiffen?
may we not stiffen?
may you not stiffen?
may they not stiffen? 	may I not be stiffening?
may you not be stiffening?
may he not be stiffening?
may we not be stiffening?
may you not be stiffening?
may they not be stiffening? 	may I not have stiffened?
may you not have stiffened?
may he not have stiffened?
may we not have stiffened?
may you not have stiffened?
may they not have stiffened? 	may I not have been stiffening?
may you not have been stiffening?
may he not have been stiffening?
may we not have been stiffening?
may you not have been stiffening?
may they not have been stiffening?