横纹肌肉瘤的特点包括() ["常见于中、老年人","青少年横纹肌肉瘤多生长于头颈部,生长快,分化差,成人多见于肢体","镜下描述为梭形细胞","治疗采取手术治疗、放射治疗、化学治疗等","干版照像有助于定位,CT有助于分期"]
空间平面相对于一个投影面的位置有哪些?各种位置的投影特性是什么?
合并脊髓损伤的脊柱骨折多发生在() ["下腰椎","胸腰段","颈段","骶尾段","胸段"]
骨肿瘤的治疗包括() ["手术治疗","化学治疗","放射治疗","中药治疗","免疫疗法"]
骨肿瘤的生长方式() ["膨胀性生长","浸润性生长","弥漫性生长","外生性生长","内生性生长"]
求Tr50³12梯形外螺纹的小径d3,中径d2,牙顶宽f,及牙槽宽W。