Regarding the aforementioned example of electricity, why is it that electrons are negatively charged, why is it that there should be such a property as charge at all, apparently with two states (positive and negative), and why is it that negatively and positively charged objects should attract each other, while objects with the same charge tend to repel each other?
(objects with the same charge; tend; to repel each other) (objects with the same charge; to repel; each other)
objects with the same charge objects with the same charge
tend to repel
to repel each other
each other