The strong acid is the active site for creaking para-diethylbenzene and ethylbenzene and it has little effect on p-isomer selectivity of disproportionation and isomerization.
强酸位是对二乙苯和乙苯裂化的活性中心，而对歧化和异构化反应生成对位异构体的选择性影响不大。
2
Site: 6 cases in sternocleidomastoid muscle, 3 cases in thyroid, 1 cases in para tracheal, 2 cases near carotid sheath, 3 cases in superficial lamella, 1 case in pre-epiglottis space.