题目

James Michener, a famous American writer donated at least 90 per cent of what he made from his 43 novels. He seemed to donate more than this. At his death, in October 1997, he had gave away US＄ 117 million. Michener made a good example, not just in how much he gave, but in his style of giving. The writer worked hard at doing good (行善). He usually follows up his donations to see how the money was used and he had a lot of fun in doing so. Michener was 90 when he died. He was the only writer on the list of American’s top 25 philanthropists (慈善家). He gave his donations to the co如图甲所示，两平行金属板A、B放在真空中，间距为d，P点在A、B板间，A板接地，B板的电势随时间t的变化情况如图乙所示，t=0时，在P点由静止释放一质量为m、电荷量为e的电子，当时，电子回到P点。电子运动过程中未与极板相碰，不计重力，则下列说法正确的是A. ：=1：2B. ：=1：3C. 在0～2T时间内，当t=T时电子的动能最大D. 在0～2T 时间内，电子的动能能增大了