A:受经济危机严重冲击
B:法西斯势力的与日俱增
C:国内阶级矛盾异常尖锐
D:民族复仇主义思潮泛滥
一带电粒子沿图中曲线穿过一匀强电场中的等势面,且四个等势面的电势关系满足φa>φb>φc>φd,若不计粒子所受重力,则( )
His father told him closely to the bears.