题目

Nearly a quarter century after a German boy threw a message in a bottle off a ship in the Baltic Sea, he's received an answer. A 13­year­old Russian, Daniil Korotkikh, was walking with his parents on a beach when he saw something lying in the sand. “I saw that bottle and it looked interesting, ” Korotkikh told The Associated Press on Tuesday.“It looked like a German beer bottle and there was a message inside.” It said, “My name is Frank, and I'm five years old.My dad and I are travelling on a ship to Denmark.If you find this letter, please write back to me, and I will wri将一带正电荷的小球在电场中由静止释放，若小球仅受电场力作用，则它在电场中运动的过程中（ ）A．始终沿电场线由高电势处向低电势处运动B．加速度始终沿电场线的切线方向C．电势能不断减小，动能不断增大D．无论电势能与动能怎样变化，两者之和始终不变