题型:填空题 多媒体教室中的投影银幕是用______(粗糙/光滑)的白布做成的.选择这种材料的优点在于:一是利用______(漫反射/镜面反射)使教室内各个座位上的同学都能看到画面;二是白布能反射______光,使同学们能看到色彩正常的画面. 查看答案
题型:单项选择题 A vessel is described as a two compartment vessel when it().A.has no more than two compartmentsB.has two compartments in addition to the engine roomC.will sink if any two compartments are floodedD.will float if any two adjacent compartments are flooded 查看答案