题目

__ __ many Chinese women have received higher education, there are still obstacles that prevent them from enjoying the same opportunities for education and employment as men． A．Whether          B．Because           C．When         D．Although 答案：D如图所示的电场，等势面是一簇互相平行的竖直平面，间隔均为d，各面电势已在图中标出，现有一质量为m的带电小球以速度v0、方向与水平方向成45°角斜向上射入电场，要使小球做直线运动，求：(1)小球应带何种电荷？电荷量是多少？(2)在入射方向上小球最大位移量是多少？(电场足够大)