English verb conjugation
MUST REFER

Regular verb: refer - referred - referred

Affirmation

Simple form	V-ing form
I must refer you must refer he must refer we must refer you must refer they must refer	I must be referring you must be referring he must be referring we must be referring you must be referring they must be referring
Perfect	V-ing perfect
I must have referred you must have referred he must have referred we must have referred you must have referred they must have referred	I must have been referring you must have been referring he must have been referring we must have been referring you must have been referring they must have been referring

Negation

Simple form	V-ing form
I must not refer you must not refer he must not refer we must not refer you must not refer they must not refer	I must not be referring you must not be referring he must not be referring we must not be referring you must not be referring they must not be referring
Perfect	V-ing perfect
I must not have referred you must not have referred he must not have referred we must not have referred you must not have referred they must not have referred	I must not have been referring you must not have been referring he must not have been referring we must not have been referring you must not have been referring they must not have been referring

Interrogative form

Simple form	V-ing form
must I refer? must you refer? must he refer? must we refer? must you refer? must they refer?	must I be referring? must you be referring? must he be referring? must we be referring? must you be referring? must they be referring?
Perfect	V-ing perfect
must I have referred? must you have referred? must he have referred? must we have referred? must you have referred? must they have referred?	must I have been referring? must you have been referring? must he have been referring? must we have been referring? must you have been referring? must they have been referring?

Interro-negative form

Simple form	V-ing form
must I not refer? must you not refer? must he not refer? must we not refer? must you not refer? must they not refer?	must I not be referring? must you not be referring? must he not be referring? must we not be referring? must you not be referring? must they not be referring?
Perfect	V-ing perfect
must I not have referred? must you not have referred? must he not have referred? must we not have referred? must you not have referred? must they not have referred?	must I not have been referring? must you not have been referring? must he not have been referring? must we not have been referring? must you not have been referring? must they not have been referring?