边运行边上下乘人的游乐设施，其运行速度应不大于（） ["0.1m\/s","0.2m\/s","0.3m\/s","0.4m\/"]
消化系统特点。
A receiving host computes the checksum on a frame and determines that the frame is damaged.The frame is then discarded.At which OSI layer did this happen?（） [" session"," network"," physical"," data link"," transport"]
什么是现场总线？常用的现场总线有哪些？
非当代消费者需求的新趋势是（） ["追求消费品的协调统一","追求时代与现代潮流","追求消费品的思想价值","追求消费的情趣"]
开元石经（开成石经）
