• 2022-06-16
    ‎两个同心均匀带电球面,半径分别为Ra和Rb(RaA: [img=94x44]1803036ceacf96f.bmp[/img]
    B: [img=102x50]1803036cf6138ea.bmp[/img]
    C: [img=121x51]1803036d02f2248.bmp[/img]
    D: [img=86x52]1803036d0cf0634.bmp[/img]
  • 举一反三