closed core type

例句：

1. 1.The new design uses a closed-core type of material to improve efficiency.
   新设计使用了闭心型材料来提高效率。
2. 2. The closed-core type of steel is stronger and more durable than its open-core counterparts.
   闭心型钢比其开心型同类产品更坚固耐用。
3. 3.The closed-core type of battery has a longer lifespan compared to the open-core ones.
   闭心型电池的寿命比开心型电池长。