第17题: [单项选择]Which of the following is the topic of Paragraph 3 A. Some historical documents may not be real. B. Some authors may not be honest. C. Historians should be careful about their sources. D. Historians may be influenced by their own backgrounds. 参考答案:C 答案解析:第三段第一句话“But the historian needs always to be in his guard not to be misled by his sources.”概括了第三段的主要