如图所示,倾角为 θ 的平行金属导轨宽度为 L ,电阻不计,底端接有阻值为 R 的定值电阻,处在与导轨平面垂直向上的磁感应强度为 B 的磁场中.有一质量为 m 、长也为 L 的导体棒始终与导轨垂直且接触良好,导体棒的电阻为 r ,它与导轨之间的动摩擦因数为 μ ,现让导体棒从导轨底部以平行于斜面的速度 v 0 向上滑行,上滑的最大距离为 s ,底端的速度为 v ,下列说法正确的是 ( )
【简答题】翻译句子 The basic transaction process of e-commerce Preparatory stage Online research before trading Market demand survey English questionnaire design
【判断题】Because the Ricardian theory of comparative advantage was based only on a nation's demand conditions, it could not fully explain the distribution of the gains from trade among trading partners.