题目

第二节 完形填空（共20小题；每小题1.5分，满分30分） Just how popular was Mini? Very. Every year, her classmates voted her  31 the favourite student. She was so easy to 32 along with that the number of friends she had by far outnumbered (压倒)those of anyone else in her group. One day the 10-year-old was  33  talking in the class and ordered to stay back as  34 . Staying back 35 doing something “useful”, like helping in the garden or library after school.    Now the school in which Mini 36  had a rule of sorts. Once a month, you could interchange your punishmen13．如图所示，电容器两极板之间的距离为d，板间电压为U，极板间的匀强磁场的磁感应强度为B1，一束电荷量相同的带正电的粒子沿图示虚线方向射入电容器，沿直线穿过电容器后从D缝进入另一磁感应强度为B2的匀强磁场，结果分别垂直打在a、b两点，两点间距离为△R．设粒子所带电量为q，且不计粒子所受重力，求打在a、b两点的粒子的质量之差．