All Henan migrant workers have obtained temporary residence permits; all those who have obtained temporary residence permits have obtained employment permits; some Henan migrant workers have become gatekeepers: some martial arts school students have become gatekeepers: all martial arts schools No trainees have obtained employment permits. If the above is true. What options cannot be determined to be true? ['Some Henan people who come to Beijing to play T are students in martial arts schools.', 'All Henan migrant workers have obtained employment permits.', 'Some gatekeepers have employment permits.', 'Some guards do not have employment permits.']