Large voids are found surrounding stacks of paper. 在纸堆周围会存在很多大的空间。
In a document copying machine or duplicator,a device that separates by friction successive sheets of paper from the paper stack and feeds them into the machine. 在文件复制机或复印机中，通过摩擦把堆叠的纸张从纸堆分开并馈入机器的一种装置。
