heavy rare earths

例句：

1. 1.The heavy rare earths are used in the production of high-performance batteries.
   重稀土元素用于生产高性能电池。
2. 2. Heavy rare earths are also used in the manufacturing of electronic devices.
   重稀土元素也被用于制造电子设备。
3. 3. The mining of heavy rare earths is a major concern for environmentalists.
   开采重稀土是环保主义者的主要关切。