An instrument for measuring variations in the gravitational field of the earth.
测量地球引力场变化的仪器。
This is an instrument for measuring variations in the gravitational field of the earth.
这是个测量地球引力场变化的仪器。
This is an instrument for measuring variations in the gravitational field of the earth.
这是个测量地球引力场变化的仪器。
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