Lesson One: Summary of DefinitionsTeaching Objectives:After studying this lesson, the students are expected to be able to 1.Use the words and expressions in the texts and skim the passage2.Translate some sentences into ChineseImportant Points:1、New words and Expressionslevel surface；curved；normal to；plumb line；deviation；vertical；mean；horizontal plane；tangent to；intersection；perpendicular to；nadir；zenith；term；elevation；Assume；Datum；Contour；Difference in elevation；Leveling ；Gradi
