Welcome to our club l Our club is a good place to have fun for students. We have ten sports teachers and five art teachers. Here you can learn to play tennis and you can learn to draw（画画）.And we have many great activities. October is a busy month. On October 5th,we have a trip in the morning. And on October 20th,we have two games, a tennis game and a baseball game. Your parents can come to the club to watch the games. On December 18t",we have a music festival. It's very interesting. And on December 23nd,we have an English party.

    In the club, we have a food store. You can have lunch or dinner here. Come and have a good time here !

搞卫生

带电小球以一定的初速度v₀竖直向上抛出，能够达到的最大高度为h_l；若加上水平方向的匀强磁场，且保持初速度仍为v_o，小球上升的最大高度为h₂；若加上水平方向的匀强电场，且保持初速度仍为v．，小球上升的最大高度为h₃，如图所示．不计空气阻力，则（   ）