1. 如图所示是水平放置三角形的直观图,[D]是[△ABC]的[BC]边中点,[AB、BC]分别与[y′]轴、[x′]轴平行,则三条线段[AB、AD、AC]中( ) A. 最长的是[AB],最短的是[AC] B. 最长的是[AC],最短的是[AB] C. 最长的是[AB],最短的是[AD] D. 最长的是[AC],最短的是[AD]
This paper describes an experimental study of heat transfers in the smooth-walled and rib-roughened helical pipes with reference to the design of enhanced cooli