填空题 Historians are detectives searching out the evidence of the past in their pursuit of history. This is a challenging and frequently engaging quest　1　its own, but evidence must be turned to　2　. Primary sources that are uncovered　3　many forms that vary　4　the questions asked and the period studied, but written records are　5　historians use more than any other. The historian does not　6　evidence in the manner of courts of law, where questions of admissibility and truth versus falsehood are　7　. The historian''s use of evidence is much more　8　 Determining how and with what end 9 mind any piece of evidence came into existence are the first tasks 10 the historian in the internal criticism of historical sources. It is important to know, for instance, who 11 a particular census and with what instructions, or　12　a correspondent was addressing a friend or foe, colleague or opponent. 　　For many years historians divided evidence into the two　13　of primary and secondary sources. The former were considered as any　14　or artifact from the period　15　 study, the latter as descriptions or reconstructions based on primary sources. The function of the historian, it was　16　, was to convert primary sources into secondary sources. This　17　misleads. What have been called secondary sources am not historical sources at all, but　18　that reveal the historian''s point of view. All evidence used by the historian was a primary source at the time it was　19　and it is always partial and incomplete. Therein lies part of the　20　of history.