Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I must fall. stumbel you must fall. stumbel he must fall. stumbel we must fall. stumbel you must fall. stumbel they must fall. stumbel
V-ing form
I must be fall. stumbeling you must be fall. stumbeling he must be fall. stumbeling we must be fall. stumbeling you must be fall. stumbeling they must be fall. stumbeling
Perfect
I must have fall. stumbeled you must have fall. stumbeled he must have fall. stumbeled we must have fall. stumbeled you must have fall. stumbeled they must have fall. stumbeled
V-ing perfect
I must have been fall. stumbeling you must have been fall. stumbeling he must have been fall. stumbeling we must have been fall. stumbeling you must have been fall. stumbeling they must have been fall. stumbeling
Negation
Simple form
I must not fall. stumbel you must not fall. stumbel he must not fall. stumbel we must not fall. stumbel you must not fall. stumbel they must not fall. stumbel
V-ing form
I must not be fall. stumbeling you must not be fall. stumbeling he must not be fall. stumbeling we must not be fall. stumbeling you must not be fall. stumbeling they must not be fall. stumbeling
Perfect
I must not have fall. stumbeled you must not have fall. stumbeled he must not have fall. stumbeled we must not have fall. stumbeled you must not have fall. stumbeled they must not have fall. stumbeled
V-ing perfect
I must not have been fall. stumbeling you must not have been fall. stumbeling he must not have been fall. stumbeling we must not have been fall. stumbeling you must not have been fall. stumbeling they must not have been fall. stumbeling
Interrogative form
Simple form
must I fall. stumbel? must you fall. stumbel? must he fall. stumbel? must we fall. stumbel? must you fall. stumbel? must they fall. stumbel?
V-ing form
must I be fall. stumbeling? must you be fall. stumbeling? must he be fall. stumbeling? must we be fall. stumbeling? must you be fall. stumbeling? must they be fall. stumbeling?
Perfect
must I have fall. stumbeled? must you have fall. stumbeled? must he have fall. stumbeled? must we have fall. stumbeled? must you have fall. stumbeled? must they have fall. stumbeled?
V-ing perfect
must I have been fall. stumbeling? must you have been fall. stumbeling? must he have been fall. stumbeling? must we have been fall. stumbeling? must you have been fall. stumbeling? must they have been fall. stumbeling?
Interro-negative form
Simple form
must I not fall. stumbel? must you not fall. stumbel? must he not fall. stumbel? must we not fall. stumbel? must you not fall. stumbel? must they not fall. stumbel?
V-ing form
must I not be fall. stumbeling? must you not be fall. stumbeling? must he not be fall. stumbeling? must we not be fall. stumbeling? must you not be fall. stumbeling? must they not be fall. stumbeling?
Perfect
must I not have fall. stumbeled? must you not have fall. stumbeled? must he not have fall. stumbeled? must we not have fall. stumbeled? must you not have fall. stumbeled? must they not have fall. stumbeled?
V-ing perfect
must I not have been fall. stumbeling? must you not have been fall. stumbeling? must he not have been fall. stumbeling? must we not have been fall. stumbeling? must you not have been fall. stumbeling? must they not have been fall. stumbeling?