题目

   Peter and Paul got permission from their parents to camp in a field close to their farm. But, being adventurous boys, they knew it would be more  41  to camp in the woods that lay beyond the river. Excitedly, the boys  42   with their tent and food.    Carrying their heavy  43  , the two brothers walked along the riverbank, hardly noticing the distance or the sun beating down. They were eager to reach their 44  before lunchtime. As they entered the cool, shadowy woods, they began to search for a suitable camping spot. Peter wanted to  45  close to the river at the ed在真空中一直线上依次排列三个点电荷A、B、C，都处于平衡状态，若三个电荷的电荷量、电性及间距都未知，则根据平衡能够断定（　　）A、A、B、C分别带什么电B、A、B、C中哪几个电荷同号、哪几个异号C、A、B、C带电荷量的大小关系D、哪一个电荷的电荷量最小