When a flash-type evaporator is to be secured for an extended period of time, the entire unit should be drained, cleaned, and （）. ["completely filled with saltwater","filled with de-scaling compound","tightly closed to exclude air","vented to the atmosphere"]
企业、事业单位、机关以及其他组织中以（）的劳动者，不分民族、种族、性别、职业、宗教信仰、教育程度，都有依法参加和组织工会的权利。 ["工资收入为主要生活来源","与用人单位建立劳动关系","工资收入为主要生活来源并且与用人单位建立劳动关系","工资收入为主要生活来源或者与用人单位建立劳动关系"]
从污水汽提塔上部进入的含硫污水，本身是一个气液平衡体系，污水（液相）中H2S浓度高，气相中H2S分压也（）。 ["高","低","变化不定","不变"]
在污水汽提塔内，污水中的H2S进入天然气中，天然气变为酸气后从（）排出进气体脱硫厂。 ["塔顶","塔底","塔中部","塔侧面"]
Condensate must be drained periodically from the air compressor receivers to prevent （）. ["second stage cylinder lockup","oil sump contamination","faulty operation of pneumatic valves","corrosion of air receiver baffle"]
试述板中分布钢筋的位置及作用？
