English verb conjugation
MUST REF

Regular verb: ref - refed - refed

Affirmation

Simple form	V-ing form
I must ref you must ref he must ref we must ref you must ref they must ref	I must be refing you must be refing he must be refing we must be refing you must be refing they must be refing
Perfect	V-ing perfect
I must have refed you must have refed he must have refed we must have refed you must have refed they must have refed	I must have been refing you must have been refing he must have been refing we must have been refing you must have been refing they must have been refing

Negation

Simple form	V-ing form
I must not ref you must not ref he must not ref we must not ref you must not ref they must not ref	I must not be refing you must not be refing he must not be refing we must not be refing you must not be refing they must not be refing
Perfect	V-ing perfect
I must not have refed you must not have refed he must not have refed we must not have refed you must not have refed they must not have refed	I must not have been refing you must not have been refing he must not have been refing we must not have been refing you must not have been refing they must not have been refing

Interrogative form

Simple form	V-ing form
must I ref? must you ref? must he ref? must we ref? must you ref? must they ref?	must I be refing? must you be refing? must he be refing? must we be refing? must you be refing? must they be refing?
Perfect	V-ing perfect
must I have refed? must you have refed? must he have refed? must we have refed? must you have refed? must they have refed?	must I have been refing? must you have been refing? must he have been refing? must we have been refing? must you have been refing? must they have been refing?

Interro-negative form

Simple form	V-ing form
must I not ref? must you not ref? must he not ref? must we not ref? must you not ref? must they not ref?	must I not be refing? must you not be refing? must he not be refing? must we not be refing? must you not be refing? must they not be refing?
Perfect	V-ing perfect
must I not have refed? must you not have refed? must he not have refed? must we not have refed? must you not have refed? must they not have refed?	must I not have been refing? must you not have been refing? must he not have been refing? must we not have been refing? must you not have been refing? must they not have been refing?