I may back you may back he may back we may back you may back they may back
V-ing form
I may be backing you may be backing he may be backing we may be backing you may be backing they may be backing
Perfect
I may have backed you may have backed he may have backed we may have backed you may have backed they may have backed
V-ing perfect
I may have been backing you may have been backing he may have been backing we may have been backing you may have been backing they may have been backing
Negation
Simple form
I may not back you may not back he may not back we may not back you may not back they may not back
V-ing form
I may not be backing you may not be backing he may not be backing we may not be backing you may not be backing they may not be backing
Perfect
I may not have backed you may not have backed he may not have backed we may not have backed you may not have backed they may not have backed
V-ing perfect
I may not have been backing you may not have been backing he may not have been backing we may not have been backing you may not have been backing they may not have been backing
Interrogative form
Simple form
may I back? may you back? may he back? may we back? may you back? may they back?
V-ing form
may I be backing? may you be backing? may he be backing? may we be backing? may you be backing? may they be backing?
Perfect
may I have backed? may you have backed? may he have backed? may we have backed? may you have backed? may they have backed?
V-ing perfect
may I have been backing? may you have been backing? may he have been backing? may we have been backing? may you have been backing? may they have been backing?
Interro-negative form
Simple form
may I not back? may you not back? may he not back? may we not back? may you not back? may they not back?
V-ing form
may I not be backing? may you not be backing? may he not be backing? may we not be backing? may you not be backing? may they not be backing?
Perfect
may I not have backed? may you not have backed? may he not have backed? may we not have backed? may you not have backed? may they not have backed?
V-ing perfect
may I not have been backing? may you not have been backing? may he not have been backing? may we not have been backing? may you not have been backing? may they not have been backing?