20.各种机械发生突然熄火或断电时,应急处置措施:( )。《铁路货物装卸安全技术规则》

各种机械发生突然熄火或断电时, 应急处置措施: The correct answer is ABD. This question deals with emergency measures to be taken when various types of machinery suddenly stall or lose power during loading and unloading operations. Option A: It advises immediately returning the controller to the "0" position and turning off the main switch when the machinery stalls or loses power unexpectedly. Option B: It suggests making the cargo descend slowly if it is suspended in the air due to the sudden stall or power failure of the machinery. Option C: This option suggests making the cargo descend urgently if it is suspended in the air, but it is not the correct option, as the correct procedure is to do it slowly (Option B). Option D: It points out that when loading and unloading machinery (such as grab buckets, hooks, buckets, electromagnets) or cargo enters restricted areas, the protective signals must not be removed. The correct answers for all three questions are ABCD, as these options represent the appropriate emergency response measures in different scenarios related to the loading and unloading of goods in railway operations.