The level of the ocean's surface, especially the level halfway between mean high and low tide, used as a standard in reckoning land elevation or sea depths.

海洋表面的水位，尤其是在平均高水位和低水位之间的平均位置的水位，用作计算陆地海拔和海水深度的标准。

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The mean of post-test has improve by 8.6667 comparing to the pre-test, and the standard deviation of the post-test decreases, which implies students' average level improves.

后测的分数明显高于前测的分数，后测平均分比前测平均分高出8.667分，而且后测的标准差小于前测，说明学生的整体水平有了提高；

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The idea here is to communicate that ultimate goal of economic production is to raise folks standard of living, by which we mean their level of consumption.

FORBES: How to Grow an Economy