验证查询：在将连接返回给调用方前用于验证连接的SQL查询。

Validation query: the SQL query that is used to validate connections before returning them to the caller.

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国民生产总值是半个世纪前制定的，帮助各国建立了衡量经济产出变化的统一方式。

Developed a half-century ago, GNP helped establish a common way among countries of measuring the change in economic output.

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另一方面，很显然“提前教育”项目的目标是让学龄前儿童做好上学的准备。

On the other hand, it is clear that Head Start is meeting its goal of getting preschoolers ready for school.

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