coarse flat file

例句：

1. 1.He used to work on a rough flat file for many years.
   他过去曾用粗糙的平文件工作了多年。
2. 2.The company has been using this rough flat file to store customer information.
   该公司一直使用这种粗糙的平文件来存储客户信息。
3. 3.The writer started with a rough flat file and worked his way up to a finished document.
   这位作家从粗糙的平文件开始，逐步完善成一份完整的文档。