You will notice that in the schematic the negative rail has 0 voltage so that setup is essentially in single rail.

你会发现在电路图中负电压是0伏，所以结构本质上是单电压。

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For example, choosing the negative rail as the ground reference may optimize the dynamic range of an op amp whose OUTPUT is designed to swing to 0v.

例如，选择负轨作为地参考也许能够优化一个输出可以至0运放的动态范围。

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An operational amplifier that can maintain stability close to its negative, or ground, rail is an important asset.

运放维持接近其负极、地或轨的稳定性是很重要的指标。

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But, negative news surrounding its rail and private finance initiatives with schools and universities, as well as the company's huge debt burden has battered its reputation.

BBC: NEWS | Business | Jarvis slides to ?246m year loss