English verb conjugation
MAY STIFFEN

Regular verb: stiffen - stiffened - stiffened

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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

Negation

Simple form	V-ing form
I mayn't stiffen you mayn't stiffen he mayn't stiffen we mayn't stiffen you mayn't stiffen they mayn't stiffen	I mayn't be stiffening you mayn't be stiffening he mayn't be stiffening we mayn't be stiffening you mayn't be stiffening they mayn't be stiffening
Perfect	V-ing perfect
I mayn't have stiffened you mayn't have stiffened he mayn't have stiffened we mayn't have stiffened you mayn't have stiffened they mayn't have stiffened	I mayn't have been stiffening you mayn't have been stiffening he mayn't have been stiffening we mayn't have been stiffening you mayn't have been stiffening they mayn't have been stiffening

Interrogative form

Simple form	V-ing form
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?
Perfect	V-ing perfect
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?

Interro-negative form

Simple form	V-ing form
mayn't I stiffen? mayn't you stiffen? mayn't he stiffen? mayn't we stiffen? mayn't you stiffen? mayn't they stiffen?	mayn't I be stiffening? mayn't you be stiffening? mayn't he be stiffening? mayn't we be stiffening? mayn't you be stiffening? mayn't they be stiffening?
Perfect	V-ing perfect
mayn't I have stiffened? mayn't you have stiffened? mayn't he have stiffened? mayn't we have stiffened? mayn't you have stiffened? mayn't they have stiffened?	mayn't I have been stiffening? mayn't you have been stiffening? mayn't he have been stiffening? mayn't we have been stiffening? mayn't you have been stiffening? mayn't they have been stiffening?