求翻译：三是重点原则，营销人员选择正确的方法和尺度对客户进行分类，选择更有价值和潜力的客户进行营销，在他们身上投入更多的关注，达到利益最大化。是什么意思？

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3 is a focus on sales and marketing personnel, select the correct methods and standards for the classification of the customer's choice of the more valuable and potential customers in their marketing, invest more, and achieve the maximum benefit.

Three is the key principle, the marketing personnel chooses the correct method and the criterion carries on the classification to the customer, the choice has the value and the potential customer carries on the marketing, enters more attention in their body upthrow, achieves the benefit maximization

Three are key principles marketers to choose the correct method and scale to classify customers, select customers more value and potential for marketing and put more focus on them, to maximize the benefits.

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