为什么这是编译时错误？publicTCastToCastMe(TSourcei){return(TCastTo)i;}错误:Cannotconverttype'TSource'to'TCastTo'为什么这是一个运行时错误？publicTCastToCastMe(TSourcei){return(TCastTo)(object)i;}inta=4;longb=CastMe(a);//InvalidCastException//thiscontrivedexampleworksintaa=4;intbb=CastMe(aa);//thisalsoworks,theproblemislim