相接built-up
相交inter section
相切tangent
相贯penetration
支架brace
底板bottom board
肋rib
支承板bearing plate
轮廓线outline, contour line
底图traced drawing
截平面cutting plane
截交线line of section
二重性dual nature
平面曲线plane curve
圆弧arc
椭圆ellipse
长轴major axis
短轴minor axis
双曲线hyperbola
抛物线parabola
圆circle
圆锥顶conic apex