研究其它时段历史的历史学家们在成文的记录和文件中发现了这一段历史的材料。
The historian of other periods finds his materials in books, in written records and documents.
可以是读了一本书、一篇文章、一段话，甚至是几句名言后，把具体的感受和得到的启示写成文章。
Can read a book, article, paragraph, or even a few famous, put the specific feelings and get inspiration written article.
对系统生命周期中的每一阶段，都应该在开发的同时安排系统验证，并形成文件。
The system verification shall be planned concurrently with the development, for each phase of the lifecycle, and shall be documented.
应用推荐