• 2022-06-19
    半径为R的带有一缺口的细圆环,缺口长为d(d<A: [img=104x38]18031694a8b44cf.jpg[/img]
    B: [img=104x38]18031694b2210d7.jpg[/img]
    C: [img=110x38]18031694ba4216f.jpg[/img]
    D: [img=110x38]18031694c2aa52a.jpg[/img]