The stability of the electron is one of the simplest yet most stringent tests of the law of charge conservation . 电子的稳定性是对电荷守恒定律的最简明而又最有说服力的检验之一。
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All of our products are subject to the most stringent testing and checking procedures before they are sold and we do not know why these problems have arisen on this occasion 我们所有的产品在销售之前，都经过了严格的检验，因此我们不知道你所购货物出现问题的原因。
