Answers

2014-08-03T12:23:49+08:00
a thing, especially a trend or fact, that indicates the state or level of something.

or


a device providing specific information on the state or condition of something, in particular.
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2014-08-03T12:24:53+08:00
chemical indicator, any substance that gives a visible sign, usually by a colour change, of the presence or absence of a threshold concentration of a chemical species, such as an acid or an alkali in a solution. An example is the substance called methyl yellow, which imparts a yellow color to an alkaline solution... hope it can help you!
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