bolt core

例句：

1. 1. The bolt core is thepart of a bolt that holds the bolthead in place.
   螺栓核心是螺栓中固定螺栓头的部件。
2. 2. The bolt core wasmade from high-quality steel to ensuredurability.
   螺栓核心由优质钢材制成，以确保耐用性。
3. 3. The bolt core was designedto be easily removed for maintenance.
   螺栓核心设计为易于拆卸以进行维护。