问题
选择题
________the economy and people's life will become better and better. [ ]
A. Develop
B. Developing
C. Developed
D. To develop
答案
答案：A
搜题请搜索小程序“爱下问搜题”
________the economy and people's life will become better and better. [ ]
A. Develop
B. Developing
C. Developed
D. To develop
答案：A
，竖直放置。x轴经过两板下边缘，坐标原点O位于两板中心线上，坐标轴F侧有垂直纸面向里的匀强磁场，磁感应强度为B。两极板间加上如图所示的电压，其中
，t=0时刻，自两板上端中点处沿两极板中心线以初速度v0连续发射带正电荷的粒子，粒子的质量为m，电荷量为q。不考虑重力的影响，粒子在通过电场区域的极短时间内，极板间的电压可看做不变。求：