I may crack you may crack he may crack we may crack you may crack they may crack
V-ing form
I may be cracking you may be cracking he may be cracking we may be cracking you may be cracking they may be cracking
Perfect
I may have cracked you may have cracked he may have cracked we may have cracked you may have cracked they may have cracked
V-ing perfect
I may have been cracking you may have been cracking he may have been cracking we may have been cracking you may have been cracking they may have been cracking
Negation
Simple form
I may not crack you may not crack he may not crack we may not crack you may not crack they may not crack
V-ing form
I may not be cracking you may not be cracking he may not be cracking we may not be cracking you may not be cracking they may not be cracking
Perfect
I may not have cracked you may not have cracked he may not have cracked we may not have cracked you may not have cracked they may not have cracked
V-ing perfect
I may not have been cracking you may not have been cracking he may not have been cracking we may not have been cracking you may not have been cracking they may not have been cracking
Interrogative form
Simple form
may I crack? may you crack? may he crack? may we crack? may you crack? may they crack?
V-ing form
may I be cracking? may you be cracking? may he be cracking? may we be cracking? may you be cracking? may they be cracking?
Perfect
may I have cracked? may you have cracked? may he have cracked? may we have cracked? may you have cracked? may they have cracked?
V-ing perfect
may I have been cracking? may you have been cracking? may he have been cracking? may we have been cracking? may you have been cracking? may they have been cracking?
Interro-negative form
Simple form
may I not crack? may you not crack? may he not crack? may we not crack? may you not crack? may they not crack?
V-ing form
may I not be cracking? may you not be cracking? may he not be cracking? may we not be cracking? may you not be cracking? may they not be cracking?
Perfect
may I not have cracked? may you not have cracked? may he not have cracked? may we not have cracked? may you not have cracked? may they not have cracked?
V-ing perfect
may I not have been cracking? may you not have been cracking? may he not have been cracking? may we not have been cracking? may you not have been cracking? may they not have been cracking?