第二章 Projection of Basic Elements：The basic elements of a solid is point, line and plane. In engineering the representation and solution of spatial problems is based on the theory of orthographic. Orthographic projection forms the basis for producing and reading engineering drawing. This chapter is concerned with orthographic projections of point, line and plane.2.1Projections of a Point:Projection of points in a three-projection-plane system[单选题]How many types of parallel line are there relative to projection plane?选项:[1, 2, 3, 4]
2.2Relative Position of Two Points:The relative position of two points on a solid is the relative position of left and right(X),front and back(Y), up and down(Z) in the space.
2.3Types of Line:We talk about three types of line, include lines parallel to a projection plane, lines perpendicular to a projection plane and general position lines.
2.4Relationship of Two Lines:we learn the relationship of two lines, include two parallel lines, two perpendicular lines and two intersection lines.
2.5Tyles of Plane:There are three types of plane,include horizontal plane, frontal plane and profile plane.
[判断题]The true length projection of a line appears in a projection plane that is parallel to the line选项:[错, 对]
[单选题]Which projection is the true length for a frontal line?选项:[W projection, H projection, no projection, V projection]
[单选题]Which projection accumulates as a point for a H perpendicular line?选项:[W, no projection accumulates as a point, H, V]
[单选题]How can you represent V projection of a point?
选项:[a', a'', a, A]
[判断题]If a line is parallel to any line in a plane, the line is parallel to the plane.选项:[错, 对]
[判断题]If two projections of two lines are parallel, then the two lines are parallel in space选项:[错, 对]
[判断题]Two lines are parallel in space provided that their respective projections on two projection planes are parallel.选项:[对, 错]
[单选题]Which coordinates are related to H projection of a point?选项:[y,z, x,y,z, x,z, x,y]
[多选题]How many relationships between two lines?选项:[4, 3, 2, 1]
