Topics for textbooks and conference books should be to the experiences and interests of th

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(答案→)A. relevant
B. concentrated
C. reliable
D. based
解析：句意：教材和参考书的主题应贴近学生的经验和兴趣。relevant有关的；贴切的。现实的；concentrated集中的；聚精会神的；reliable可信赖的；可靠的；确实的；based on有根基的;有基地的。