English verb conjugation
MUST PLUMB

Regular verb: plumb - plumbed - plumbed

Affirmation

Simple form	V-ing form
I must plumb you must plumb he must plumb we must plumb you must plumb they must plumb	I must be plumbing you must be plumbing he must be plumbing we must be plumbing you must be plumbing they must be plumbing
Perfect	V-ing perfect
I must have plumbed you must have plumbed he must have plumbed we must have plumbed you must have plumbed they must have plumbed	I must have been plumbing you must have been plumbing he must have been plumbing we must have been plumbing you must have been plumbing they must have been plumbing

Negation

Simple form	V-ing form
I must not plumb you must not plumb he must not plumb we must not plumb you must not plumb they must not plumb	I must not be plumbing you must not be plumbing he must not be plumbing we must not be plumbing you must not be plumbing they must not be plumbing
Perfect	V-ing perfect
I must not have plumbed you must not have plumbed he must not have plumbed we must not have plumbed you must not have plumbed they must not have plumbed	I must not have been plumbing you must not have been plumbing he must not have been plumbing we must not have been plumbing you must not have been plumbing they must not have been plumbing

Interrogative form

Simple form	V-ing form
must I plumb? must you plumb? must he plumb? must we plumb? must you plumb? must they plumb?	must I be plumbing? must you be plumbing? must he be plumbing? must we be plumbing? must you be plumbing? must they be plumbing?
Perfect	V-ing perfect
must I have plumbed? must you have plumbed? must he have plumbed? must we have plumbed? must you have plumbed? must they have plumbed?	must I have been plumbing? must you have been plumbing? must he have been plumbing? must we have been plumbing? must you have been plumbing? must they have been plumbing?

Interro-negative form

Simple form	V-ing form
must I not plumb? must you not plumb? must he not plumb? must we not plumb? must you not plumb? must they not plumb?	must I not be plumbing? must you not be plumbing? must he not be plumbing? must we not be plumbing? must you not be plumbing? must they not be plumbing?
Perfect	V-ing perfect
must I not have plumbed? must you not have plumbed? must he not have plumbed? must we not have plumbed? must you not have plumbed? must they not have plumbed?	must I not have been plumbing? must you not have been plumbing? must he not have been plumbing? must we not have been plumbing? must you not have been plumbing? must they not have been plumbing?