There was a significantly negative correlation between V-C and titrationable acid, titrationable acid could be used as an indirect trait for selecting V-C.

可滴定酸与V-C之间存在着显著的负相关，通过对可滴定酸的选择可间接地对V-C进行选择；

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Remark and evaluation about the essentials of the indirect correlation and the way recommendable to the direct correlation were made in this paper.

文中评述了间接对比方法的各个步骤的要点及直接对比方法的可能途径。

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