n. 坡度?? Lesson One Lesson One : : Summary of Definitions Summary of Definitions Text Text ? Part 1: – Definition of level surface (para 1) – A level surface is a curved surface, every element of which is normal to a plumb line, disregarding local deviations of the plumb line from the vertical with the mean spheroid surface of the earth. –水准面是弯曲的表面,水准面上的每一个元素都与铅垂线垂直,(这种垂直关系)是假定不考虑某处的铅垂线与地球平均旋转椭球面的垂线间的偏差。?? Lesson One Lesson One : : Summary of Definitions Summary of Definitions The picture of level surface ?? Lesson One Lesson One : : Summary of Definitions Summary of Definitions ? Part 2 : – Definitions of horizontal plane 、 horizontal line and angle (Para2 、 3 and 4) – A horizontal plane is a plane tangent to a level surface at a particular point. –水平面是在特定点上相切于水准面的平面.
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