I may refer you may refer he may refer we may refer you may refer they may refer
V-ing form
I may be referring you may be referring he may be referring we may be referring you may be referring they may be referring
Perfect
I may have referred you may have referred he may have referred we may have referred you may have referred they may have referred
V-ing perfect
I may have been referring you may have been referring he may have been referring we may have been referring you may have been referring they may have been referring
Negation
Simple form
I may not refer you may not refer he may not refer we may not refer you may not refer they may not refer
V-ing form
I may not be referring you may not be referring he may not be referring we may not be referring you may not be referring they may not be referring
Perfect
I may not have referred you may not have referred he may not have referred we may not have referred you may not have referred they may not have referred
V-ing perfect
I may not have been referring you may not have been referring he may not have been referring we may not have been referring you may not have been referring they may not have been referring
Interrogative form
Simple form
may I refer? may you refer? may he refer? may we refer? may you refer? may they refer?
V-ing form
may I be referring? may you be referring? may he be referring? may we be referring? may you be referring? may they be referring?
Perfect
may I have referred? may you have referred? may he have referred? may we have referred? may you have referred? may they have referred?
V-ing perfect
may I have been referring? may you have been referring? may he have been referring? may we have been referring? may you have been referring? may they have been referring?
Interro-negative form
Simple form
may I not refer? may you not refer? may he not refer? may we not refer? may you not refer? may they not refer?
V-ing form
may I not be referring? may you not be referring? may he not be referring? may we not be referring? may you not be referring? may they not be referring?
Perfect
may I not have referred? may you not have referred? may he not have referred? may we not have referred? may you not have referred? may they not have referred?
V-ing perfect
may I not have been referring? may you not have been referring? may he not have been referring? may we not have been referring? may you not have been referring? may they not have been referring?