By Pallab Ghosh, BBC Science Correspondent

媒体英语会带大家一起学习BBC撰稿人在报道世界大事时常用到的单词和短语。

Background：科学家们最近在研究新一代的抗生素。这种抗生素将会使用一种在地球上存活了2亿多年的动物 – 青蛙。科学家们将从青蛙体内自身的抵抗系统里提炼出一种天然抗生素。

Frogs protect themselves by secreting chemicals that kill germs on their skin. So the theory is that some of these chemicals could be used as antibiotics.

To find out, researchers in the United Arab Emirates asked colleagues across the world to swab any frogs they found and send them their secretions. They received samples from more than six thousand different species and identified more than a hundred germ-killing chemicals.

Because they've not been used to combat human diseases before, it's hoped that they might be able to kill bacteria that had become drug-resistant.

One problem though is that many of these newly-identified chemicals are toxic. So the next step will be to adapt them to make them benign to patients but lethal to bacteria.

The researchers point out that their work highlights the importance of preserving frog diversity. They say that many species whose skin might contain potentially valuable medicinal substances may become extinct soon because of a loss of habitat and water pollution.

• contain [kən´tein]   v.包含；容纳；抑制   (初中英语单词)
• valuable [´væljuəbəl, -jubəl]   a.有价值的，贵重的   (初中英语单词)
• species [´spi:ʃi:z]   n.(生物的)种，类   (高中英语单词)
• combat [´kɔmbæt]   v.&n.斗争；战斗；争斗   (高中英语单词)
• bacteria [bæk´tiəriə]   n.细菌   (英语四级单词)
• extinct [ik´stiŋkt]   a.熄灭的；灭绝的   (英语四级单词)
• diversity [dai´və:siti]   n.差异；多样性   (英语六级单词)