This metallic core gives Earth its characteristic magnetic field, which has played an extremely important role in the history of our planet.
这种金属核赋予地球特有的磁场，在地球的历史上发挥了极其重要的作用。
2
"The" rare earth elements "are a group of 17 naturally occurring metallic elements used in small amounts in everything from high-powered magnets to batteries and electronic circuits."
“稀土”是一种自然产生的17组金属元素，从大马力磁铁电池到电子电路都会使用。
3
Rare earth, an nonrenewable resource, is a general name for 17 low-reserve metallic elements.