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"]
倭寇从哪个时代横行在中国沿海：（） ["清代","明代","宋代","唐代"]
开元石经（开成石经）
正始石经
举例说明词义的过度扩张、词义的过度缩小和语言的过度规则化。
什么是现场总线？常用的现场总线有哪些？
