frictions
If there is friction between people, there is disagreement and argument between them.
Sara sensed that there had been friction between her children.
萨拉感觉到她的孩子们之间有过争执。
Friction is the force that makes it difficult for things to move freely when they are touching each other.
The pistons are graphite-coated to reduce friction.
活塞表面涂有石墨以减少摩擦。