Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I must enthusiasm you must enthusiasm she must enthusiasm we must enthusiasm you must enthusiasm they must enthusiasm
V-ing form
I must be enthusiasming you must be enthusiasming she must be enthusiasming we must be enthusiasming you must be enthusiasming they must be enthusiasming
Perfect
I must have enthusiasmed you must have enthusiasmed she must have enthusiasmed we must have enthusiasmed you must have enthusiasmed they must have enthusiasmed
V-ing perfect
I must have been enthusiasming you must have been enthusiasming she must have been enthusiasming we must have been enthusiasming you must have been enthusiasming they must have been enthusiasming
Negation
Simple form
I must not enthusiasm you must not enthusiasm she must not enthusiasm we must not enthusiasm you must not enthusiasm they must not enthusiasm
V-ing form
I must not be enthusiasming you must not be enthusiasming she must not be enthusiasming we must not be enthusiasming you must not be enthusiasming they must not be enthusiasming
Perfect
I must not have enthusiasmed you must not have enthusiasmed she must not have enthusiasmed we must not have enthusiasmed you must not have enthusiasmed they must not have enthusiasmed
V-ing perfect
I must not have been enthusiasming you must not have been enthusiasming she must not have been enthusiasming we must not have been enthusiasming you must not have been enthusiasming they must not have been enthusiasming
Interrogative form
Simple form
must I enthusiasm? must you enthusiasm? must she enthusiasm? must we enthusiasm? must you enthusiasm? must they enthusiasm?
V-ing form
must I be enthusiasming? must you be enthusiasming? must she be enthusiasming? must we be enthusiasming? must you be enthusiasming? must they be enthusiasming?
Perfect
must I have enthusiasmed? must you have enthusiasmed? must she have enthusiasmed? must we have enthusiasmed? must you have enthusiasmed? must they have enthusiasmed?
V-ing perfect
must I have been enthusiasming? must you have been enthusiasming? must she have been enthusiasming? must we have been enthusiasming? must you have been enthusiasming? must they have been enthusiasming?
Interro-negative form
Simple form
must I not enthusiasm? must you not enthusiasm? must she not enthusiasm? must we not enthusiasm? must you not enthusiasm? must they not enthusiasm?
V-ing form
must I not be enthusiasming? must you not be enthusiasming? must she not be enthusiasming? must we not be enthusiasming? must you not be enthusiasming? must they not be enthusiasming?
Perfect
must I not have enthusiasmed? must you not have enthusiasmed? must she not have enthusiasmed? must we not have enthusiasmed? must you not have enthusiasmed? must they not have enthusiasmed?
V-ing perfect
must I not have been enthusiasming? must you not have been enthusiasming? must she not have been enthusiasming? must we not have been enthusiasming? must you not have been enthusiasming? must they not have been enthusiasming?