... essential mineral 基本矿物 essential species主要种 essentiality 本性；必要性；实质性；要点；精髓 ...
双语例句
1
Predators are an essential factor in maintaining communities that are rich and diverse in species.
捕食者是维持群落物种丰富多样的一个重要因素。
2
They prevent fish migrations and change aquatic habitats essential for native species.
它们阻止了鱼类迁徙，并改变了对本地物种至关重要的水生栖息地。
3
Such assistance was essential in identifying potential dangers—poisonous species, unpredictable rivers, uncharted territories—which could mean the difference between life and death.