1. What are the main features of modern information resources? A: The overall characteristics of modern information resources are: first, the number is huge and the growth is rapid; Second, it has strong timeliness and frequent metabolism; Third, widely dispersed and overlapping; Fourth, the items are scattered and orderly distributed; Fifth, there are various forms and complicated languages. 2. From the external characteristics of literature, what are the retrieval ways? A: There are several ways to retrieve documents from their external characteristics: title, author, institution (author unit), serial number and publication name. 3. From the content characteristics of documents, what are the general retrieval methods? A: There are several ways to retrieve the content characteristics of documents: classification, topic and keyword.