设真空中点电荷+q1和点电荷+q2相距2a,且q2=2q1,以+q1为中心、a为半径 发布时间:2017-06-09 03:10 │ 来源:www.tikuol.com 题型:单项选择题 问题: 设真空中点电荷+q1和点电荷+q2相距2a,且q2=2q1,以+q1为中心、a为半径形成封闭锋面,则通过该球面的电通量为:()。A.3q1B.2q1C.q1D.0
题型:单项选择题 We _____________ martial arts at the gym when we heard the news. [ ]A. are playing B. are doing C. were playing D. were doing 查看答案