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Art Beat in January 2016 Beijing Youth choir to perform The youth choir of China National Symphony Orchestra will soon perform classics including the Mexican folk song, The Golden Nightingale, and the Blue Danube, adapted from a waltz by Johann Strauss II. Pianists Zhao Lin and Wang Tianyang will join in the show. 7:30 pm, Jan 23. Forbidden City Concert Hall, inside Zhongshan Park, west of Tian'anmen Square, Xicheng district. 010-6559-8285. Orchestra recitals The China National Center for the Performing Arts Orchestra led by conductor Lyu Jia will give two recitals, featuring works in（2003?常州）初三（2）班物理实践小组在装置直流电动机模型后参加班级的实践成果展示交流会，在会上演示通过改变电动机的转动方向及转速使重物上升或下降的过程，如图A所示，关于控制电动机的电路，可以有如下两种设计方案，方案一的电路元件见图B甲，有两个单刀双掷开关（当触片K1接通a时触片K2接通c，当触片K1接通b时触片K2接通d）和一个电源．方案三的电路元件见图B乙，只有一个单刀双掷开关（触片K接通a，或接通b），但有两个电源，请你任选其中一个设计方案（多选无效）完成电路图的连接．（操作过程中不得再改变电路中的接线）并请回答：（1）如何改变电动机的转向方向？（2）如何改变电动机的转速？