Conjugación del verbo inglés
MUST STIFFEN

Verbo regular: stiffen - stiffened - stiffened

Afirmación

Forma simple	Forma con V-ing
I must stiffen you must stiffen she must stiffen we must stiffen you must stiffen they must stiffen	I must be stiffening you must be stiffening she must be stiffening we must be stiffening you must be stiffening they must be stiffening
Perfecto	Perfecto con V-ing
I must have stiffened you must have stiffened she 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 she must have been stiffening we must have been stiffening you must have been stiffening they must have been stiffening

Negación

Forma simple	Forma con V-ing
I mustn't stiffen you mustn't stiffen she 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 she mustn't be stiffening we mustn't be stiffening you mustn't be stiffening they mustn't be stiffening
Perfecto	Perfecto con V-ing
I mustn't have stiffened you mustn't have stiffened she 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 she 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 simple	Forma con V-ing
must I stiffen? must you stiffen? must she stiffen? must we stiffen? must you stiffen? must they stiffen?	must I be stiffening? must you be stiffening? must she be stiffening? must we be stiffening? must you be stiffening? must they be stiffening?
Perfecto	Perfecto con V-ing
must I have stiffened? must you have stiffened? must she 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 she have been stiffening? must we have been stiffening? must you have been stiffening? must they have been stiffening?

Forma interro-negativa

Forma simple	Forma con V-ing
mustn't I stiffen? mustn't you stiffen? mustn't she 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 she be stiffening? mustn't we be stiffening? mustn't you be stiffening? mustn't they be stiffening?
Perfecto	Perfecto con V-ing
mustn't I have stiffened? mustn't you have stiffened? mustn't she 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 she have been stiffening? mustn't we have been stiffening? mustn't you have been stiffening? mustn't they have been stiffening?