adj.空的；未填充的
Something canceled, especially a released accommodation or an unfilled appointment. 撤消被撤消的事物，尤指被放棄的住房或未履行的約會(huì)
An accumulation, especially of unfinished work or unfilled orders. 積壓堆積物，尤指沒(méi)完成的工作或未兌現(xiàn)的定單
