题目

阅读理解Electricaldevices(仪器)could soon use power made by human energy. Scientists say they havedeveloped an experimental device that produces electricity from the physicalmovement of a person walking , British scientist Max Donelan and otherscientists in Canada and the United States developed the device. Thedevice connects to a person's knee. As the person walks , the device capturesenergy each time the person slows down. To do this , the device helps with theslowing down movement of the leg, the movements of the walking person pushparts of a small machine that produces electricity. U有甲、乙两个物体，它们的体积之比是5：3，密度之比是3：2，那么甲、乙两物体的质量之比是（　　）A．2：5B．5：2C．5：6D．6：15