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 must not tough you must not tough she must not tough we must not tough you must not tough they must not tough	I must not be toughing you must not be toughing she must not be toughing we must not be toughing you must not be toughing they must not be toughing
Perfect	V-ing perfect
I must not have toughed you must not have toughed she must not have toughed we must not have toughed you must not have toughed they must not have toughed	I must not have been toughing you must not have been toughing she must not have been toughing we must not have been toughing you must not have been toughing they must not 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
must I not tough? must you not tough? must she not tough? must we not tough? must you not tough? must they not tough?	must I not be toughing? must you not be toughing? must she not be toughing? must we not be toughing? must you not be toughing? must they not be toughing?
Perfect	V-ing perfect
must I not have toughed? must you not have toughed? must she not have toughed? must we not have toughed? must you not have toughed? must they not have toughed?	must I not have been toughing? must you not have been toughing? must she not have been toughing? must we not have been toughing? must you not have been toughing? must they not have been toughing?