蛛网膜囊肿好发于（） ["鞍上池","上矢状窦","颅前凹底","颅后凹","颅中凹"] 正常人直立时，哪些椎体的棘突为水平位（） ["颈椎，全部胸椎和上4个腰椎","颈椎，上4个胸椎和下4个腰椎","前2个颈椎.全部胸椎和下4个腰椎","颈椎和腰椎","颈椎，上3个胸椎和全部腰椎"] 不属于阻塞性肺气肿的体征是（） ["桶状胸","触觉语颤增强","肺下界和肝浊音界下降","叩诊呈过清音、心浊音界缩小或不易叩出","肺泡呼吸音降低，呼气明显延长"] 连续骶管阻滞后，容易发生哪种并发症（） ["头痛","感染","硬膜外脓肿","蛛网膜炎","马尾神经综合征"] 蒸汽中的杂质有何危害？ 厂房的（）决定屋架的跨度和吊车的轨距。