要证明硬脂酸具有酸性，可采用的正确实验是(    )

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='21786' and id < 1898026 and id<>'1898026' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='21786' and id > 1898026 and id<>'1898026' order by id asc limit 5