题目

语法填空 There are about 100 million middle-aged women dancing in parks and on squares in China, and Deborah Roundy, U.S retired school teacher, is one of them. Mrs. Roundy is the only foreigner on the Shanghai dance team at Tongji University, where she is (current) teaching English. Mrs. Roundy ran upon a dozen or so middle-aged women dancing the tunes of Chinese songs in 2012. At the time, she didn't feel used to the new environment and wanted to have some fun in her life. She (invite) to join the dancing team. At first, Mrs. Roundy communicated with her teammates by(exchange) notes t16．在如图（a）所示的电路中，电源电压为15V恒定不变，R1的阻值为10欧，滑动变阻器上标有“50Ω 1A”字样，闭合电键S后，电压表V1的示数如图（b）所示．①求通过R1的电流1；②求此时R2消耗的电功率P2；③现将同样规格的电压表V2接入电路中，不改变V1量程，调节滑片P的位置，使两电压表指针偏离0刻度线的角度相同，且电路元件均正常工作，求R2连入电路中的阻值．