That like charges repel but oppositecharges attract is one of the fundamental law of electricity.
同性电荷相斥,异性电荷相吸,是电学的一个基本规律。
2
The upper and lower rings have oppositecharges, which allow the motor to contract and release, alternately tugging at the DNA like a ring of hands pulling on a rope.
高环和低环具有相反的电荷,这样的特性可以使其像拉绳子的两只手一样交替地拉住DNA。
3
They are exactly alike except that they have opposite electrical charges.