English verb conjugation
MUST TOUGH

Regular verb: tough - toughed - toughed

Affirmation

Simple form	V-ing form
I must tough you must tough she must tough we must tough you must tough they must tough	I must be toughing you must be toughing she must be toughing we must be toughing you must be toughing they must be toughing
Perfect	V-ing perfect
I must have toughed you must have toughed she must have toughed we must have toughed you must have toughed they must have toughed	I must have been toughing you must have been toughing she must have been toughing we must have been toughing you must have been toughing they must have been toughing

Negation

Simple form	V-ing form
I mustn't tough you mustn't tough she mustn't tough we mustn't tough you mustn't tough they mustn't tough	I mustn't be toughing you mustn't be toughing she mustn't be toughing we mustn't be toughing you mustn't be toughing they mustn't be toughing
Perfect	V-ing perfect
I mustn't have toughed you mustn't have toughed she mustn't have toughed we mustn't have toughed you mustn't have toughed they mustn't have toughed	I mustn't have been toughing you mustn't have been toughing she mustn't have been toughing we mustn't have been toughing you mustn't have been toughing they mustn't have been toughing

Interrogative form

Simple form	V-ing form
must I tough? must you tough? must she tough? must we tough? must you tough? must they tough?	must I be toughing? must you be toughing? must she be toughing? must we be toughing? must you be toughing? must they be toughing?
Perfect	V-ing perfect
must I have toughed? must you have toughed? must she have toughed? must we have toughed? must you have toughed? must they have toughed?	must I have been toughing? must you have been toughing? must she have been toughing? must we have been toughing? must you have been toughing? must they have been toughing?

Interro-negative form

Simple form	V-ing form
mustn't I tough? mustn't you tough? mustn't she tough? mustn't we tough? mustn't you tough? mustn't they tough?	mustn't I be toughing? mustn't you be toughing? mustn't she be toughing? mustn't we be toughing? mustn't you be toughing? mustn't they be toughing?
Perfect	V-ing perfect
mustn't I have toughed? mustn't you have toughed? mustn't she have toughed? mustn't we have toughed? mustn't you have toughed? mustn't they have toughed?	mustn't I have been toughing? mustn't you have been toughing? mustn't she have been toughing? mustn't we have been toughing? mustn't you have been toughing? mustn't they have been toughing?