By Richard Black, BBC Environment 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: 背景：新的调查研究显示全世界蛇的总量在逐日减少。专家们在对欧洲、非洲和澳洲的8种蛇类进行考察后发现在过去15年中蛇的数量在这些地方骤减。

1998 seems to be the year when things started going wrong for the world's snakes.

Numbers of species such as European asps and west African vipers began falling then and in some places have plummeted since, by as much as ninety percent.

Some of the declines are clearly due to the spread of human settlements, but others have occurred in national parks and protected areas.

The scientists behind the study, which is published in the journal Biology Letters, say they have no idea what could be causing the trend.

Climate change is a possibility, as 1998 was an unusually hot year.

A similar declinenoted a couple of decades ago in frogs was subsequently found to be due to the spread of a hitherto unknown disease, but there's no evidence yet for anything similar in snakes.

The scientists are calling for other researchers in other parts of the world to put forward any data they may have, in order to better understand the phenomenon and perhaps begin to detect what's causing it.

• european [juərə´pi:ən]   a.欧洲的 n.欧洲人   (初中英语单词)
• journal [´dʒə:nəl]   n.日记；日报；杂志   (初中英语单词)
• possibility [,pɔsə´biliti]   n.可能(性)；希望；前途   (初中英语单词)
• environment [in´vaiərənmənt]   n.郊区；周围；条件   (高中英语单词)
• species [´spi:ʃi:z]   n.(生物的)种，类   (高中英语单词)
• subsequently [´sʌbsikwəntli]   a.其次，接着   (高中英语单词)
• hitherto [,hiðə´tu:]   ad.至今，迄今   (高中英语单词)
• phenomenon [fi´nɔminən]   n.现象；奇迹；珍品   (高中英语单词)
• detect [di´tekt]   vt.发觉；侦察   (高中英语单词)
• biology [bai´ɔlədʒi]   n.生物学，生态学   (英语四级单词)
• unusually [ʌn´ju:ʒuəli]   ad.异常地；非常   (英语四级单词)
• calling [´kɔ:liŋ]   n.点名；职业；欲望   (英语六级单词)