The force of gravity makes things fall to earth.

地心引力使物体落向地面。

It is gravitation that causes the apple to fall.

是地心吸引力使苹果下落。

The geotropism growth was a response of hypha to gravity and the geotropic sensitive was at the hyphal apex.

丛枝菌根真菌菌丝延伸生长部位是菌丝尖端，其生长的向地性是对地心引力的应，应的敏部位也在生长菌丝的尖端。

This dissertation presents the theory and method on the establishment of height datums.And some problems on the geocenter motion are also studied.

本文系统地研究了建立高程基准的理论与方法、地心运动规律及其对高程基准的影响等有关问题。

Height is a measurement at right angles to this surface, and though gravity pulls mainly toward the centre of the earth, the geocentre, there are local variations.

高程是一个垂直于这个表面的测度，而力总是将物体向地心方向拉，但局部总会有一些变化。