[译] 地心引力指的是地球把每一粒子或物体保留于地球表面的吸引力。
[误] The attraction that the earth has for every particle or body on its surface is meant by gravity.

[正] By gravity is meant the attraction that the earth has for every particle or body on its surface.
[注] by...is meant...（所谓……意指）是一个惯用语，主谓语须倒装。如：By necrosis is meant the local death of cells.所谓坏死指的是细胞局部死亡。