S old iers in ancient Greece used polished shields to send battle orders to each other over vast distances in the form of flashes of sunlight.
早在古希腊，相距较远的士兵通过利用抛光的盾牌来产生闪光信号传达作战命令。
The coordinate reference datum on which precision GPS survey is based, is ITRF International Terrestrial reference Frame that IERS offers.
高精度GPS测量所依据的坐标参考基准，是由IERS所提供的ITRF国际地球参考框架。
The coordinate reference datum on which precision GPS survey is based, is ITRF International Terrestrial reference Frame that IERS offers.
高精度GPS测量所依据的坐标参考基准，是由IERS所提供的ITRF国际地球参考框架。
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