Besides, according to the result of the calculating example, a discussion is made about how to determine the mean year of the different observation periods and how to choose the leveling lines.

此外，根据实例计算的结果，讨论了有关中心年代的选取以及观测路线的取舍等问题。

youdao

That had not been observed before with the leveling data, because they didn't run leveling lines on the levees.

NPR: Satellite Imagery Shows a Sinking New Orleans

They accelerated their expansion of cell services, while leveling out land lines.

FORBES: Telecom Economic Forecast, 2013-2014