下咽癌中以哪一区发生的癌分化较差() ["下咽后壁","下咽侧壁","梨状窝区","环后区","侧后区"] 早期下咽癌（T1N0M0）的治疗方案取() ["根治性手术","根治性放疗","根治性化疗","放疗+手术综合治疗","化疗+手术综合治疗"] 下咽癌术前放射剂量选用() ["30Gy ","40~50Gy ","60Gy ","70Gy ","80Gy "] 一鼻咽癌肿瘤延至口咽，上颈有转移淋巴结，最初照射野最好采用() ["双耳前野+双颈垂直野","双耳前野+颈切线野","面颈联合野+下颈、锁骨上切线野","双耳前野+面前品字野+颈部切线野","双耳前野+双耳后野+颈部切线野"] 鼻咽癌的正常解剖分为几个壁() ["2个壁","3个壁","4个壁","5个壁","6个壁"] 原发于软腭的恶性肿瘤除鳞癌外尚多见()