题目

阅读下面短文，在空白处填入一个适当的词，或填入括号中所给的单词的正确形式。There is saying “No sports, no life”.【1】(do) sports is very important to us. Sports help us stay 【2】(health) and get good grades. Everyone in our class 【3】(love) sports. PE is one of our favorite 【4】(subject). We only have PE lessons 【5】(two)a week , but we play sports every day. Basketball is the 【6】popular sport in our class.The boys are interested in 【7】(play)it, and many girls like it, too. Another popular sport is football and there【8】a lot of 如图所示，竖直平面内，两竖直线MN、PQ间（含边界）存在竖直向上的匀强电场和垂直于竖直平面向外的匀强磁场，MN、PQ间距为d，电磁场上下区域足够大。一个质量为m、电量为q的带正电小球从左侧进入电磁场，初速度v与MN夹角θ=60°，随后小球做匀速圆周运动，恰能到达右侧边界PQ并从左侧边界MN穿出。不计空气阻力，重力加速度为g。求：（1）电场强度大小E；（2）磁场磁感应强度大小B；（3）小球在电磁场区域运动的时间t．