The external flotation bladder on an immersion suit should be inflated（）. ["before you enter the water","after you enter the water","after one hour in the water","after you notice that your suit is losing buoyancy"]
Prior to lighting off a cold automatically fired auxiliary boiler, you should （）. ["check and regulate the water level","close the air cock once fires are lit","blowdown the gage glass","crack the steam stop to assure protective steam flow"]
满堂脚手架搭设高度超过12m时，在顶层和竖向每隔（）步应设置连续的水平剪刀撑。 ["A.5","B.4","C.3","D.2"]
锅炉并汽前应冲洗水位表，并使水位维持在正常水位线（），使启动锅炉蒸气压力（）蒸气总管内汽压。 ["以下；稍低于","以下；稍高于","以上；稍低于","以上；稍高于"]
CRH1动车组配置的智能显示单元（IDU）有哪几种状态模式？
简述焦炉耐材理化指标有哪些？
