His parents are strict him.
A:with
B:to
C:at
D:by
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( )
What's the matter with your____(心脏),Jenny?
从气候、地理条件分析,世界上人口主要分布在( )