散: 散动词1.(由聚集而分离) break up; disperse 短语和例子大家别走散了。 let's not get separated. 会还没有散。 the meeting is not over yet. 警察到达时集会就散了。 the party broke up when police arrived. 乌云散了。 dark clouds dispersed.2
垂直: perpendicular; vertical; squareness; verticality; perpendicularity 短语和例子两线垂直相交。the two lines meet at right angles. 设 ab 垂直于 cd。let ab be perpendicular to cd. 当表面与射线垂直时，射线的强度最大。when a surfa
