English verb conjugation
MUST TOUGHEN

Regular verb: toughen - toughened - toughened

Affirmation

Simple form	V-ing form
I must toughen you must toughen she must toughen we must toughen you must toughen they must toughen	I must be toughening you must be toughening she must be toughening we must be toughening you must be toughening they must be toughening
Perfect	V-ing perfect
I must have toughened you must have toughened she must have toughened we must have toughened you must have toughened they must have toughened	I must have been toughening you must have been toughening she must have been toughening we must have been toughening you must have been toughening they must have been toughening

Negation

Simple form	V-ing form
I mustn't toughen you mustn't toughen she mustn't toughen we mustn't toughen you mustn't toughen they mustn't toughen	I mustn't be toughening you mustn't be toughening she mustn't be toughening we mustn't be toughening you mustn't be toughening they mustn't be toughening
Perfect	V-ing perfect
I mustn't have toughened you mustn't have toughened she mustn't have toughened we mustn't have toughened you mustn't have toughened they mustn't have toughened	I mustn't have been toughening you mustn't have been toughening she mustn't have been toughening we mustn't have been toughening you mustn't have been toughening they mustn't have been toughening

Interrogative form

Simple form	V-ing form
must I toughen? must you toughen? must she toughen? must we toughen? must you toughen? must they toughen?	must I be toughening? must you be toughening? must she be toughening? must we be toughening? must you be toughening? must they be toughening?
Perfect	V-ing perfect
must I have toughened? must you have toughened? must she have toughened? must we have toughened? must you have toughened? must they have toughened?	must I have been toughening? must you have been toughening? must she have been toughening? must we have been toughening? must you have been toughening? must they have been toughening?

Interro-negative form

Simple form	V-ing form
mustn't I toughen? mustn't you toughen? mustn't she toughen? mustn't we toughen? mustn't you toughen? mustn't they toughen?	mustn't I be toughening? mustn't you be toughening? mustn't she be toughening? mustn't we be toughening? mustn't you be toughening? mustn't they be toughening?
Perfect	V-ing perfect
mustn't I have toughened? mustn't you have toughened? mustn't she have toughened? mustn't we have toughened? mustn't you have toughened? mustn't they have toughened?	mustn't I have been toughening? mustn't you have been toughening? mustn't she have been toughening? mustn't we have been toughening? mustn't you have been toughening? mustn't they have been toughening?