题目

SINGAPORE—It seems the financial crisis isn’t all hopeless: one in four people are glad the world’s economy turned down like it did, because it helped them realize more in life, according to a global survey. Market research firm Synovate surveyed around 11400 people across the world and found more than half had permanently changed their attitudes toward money over the last 12 months. Another 47 percent, however, said they were looking forward to being able to spend freely again. “The psychology of global depression has changed the way many people do things,” Jenny Chang, managing dir如图所示是两个横截面分别为圆和正方形但磁感应强度均相同的匀强磁场，圆的直径D等于正方形的边长，两个电子分别以相同的速度飞入两个磁场区域，速度方向均与磁场方向垂直，进入圆形磁场区域的速度方向对准了圆心，进入正方形磁场区域的方向是沿一边的中点且垂直于边界线，则下列判断正确的是 (　 )A. 两电子在两磁场中运动时，其半径一定相同B. 两电子在两磁场中运动的时间一定不相同C. 进入圆形磁场区域的电子一定先飞离磁场D. 进入圆形磁场区域的电子一定不会后飞出磁场