fastenings

例句：

1. 1.The car's engine is bolted to the frame.
   汽车的引擎被螺栓固定在车架上。
2. 2. The screws on the door are tight.
   门上的螺丝紧固。
3. 3.Fasteners are used to attach things together.
   紧固件用于将物体连接在一起。