物质核心是磁性铁镍合金复合材料的结晶，其核心不是中空的。

The physical core is crystallized in magnetic iron-nickel alloy-composite. The core is not hollow.

youdao

物质核心是磁性铁镍合金复合材料的结晶，其核心不是中空的。

The physical core is crystallized in magnetic iron-nickel alloy-composite. The core is not hollow.

youdao