Which two features characterize controller-based deployments in a WLAN?（） ["coverage of large areas","individual device configuration","roaming that is facilitated bywirelee-location services","coverage ofA single area","seamless roaming throughout the network"]
加工中心的刀具由（）管理。 ["软件","PLC","硬件","ATC"]
压实砂砾石坝壳时，砂石料的含水量必须保持为最优含水量。
患者，男性，35岁，车祸致呼吸困难，面色苍白，血压下降，尿量减少，脉搏细数。经检查，临床诊断为右侧第4、5肋骨骨折并损伤性血胸。立即输液、输血，行胸膜腔闭式引流术。下列哪一项（）不是进行性胸腔出血的特点 ["脉搏逐渐增快，血压持续下降","经扩容后血压有回升，但扩容结束后又下降","血红蛋白，血红细胞计数及血细胞比容持续下降","胸腔闭式引流抽出血量≥200ml\/h，并持续2～3h或以上","引流液的颜色越来越淡。"]
何谓视差？ 产生视差的原因是什么？怎样消除视差？
反刍过程
