英语听力精选进阶版 7159（在线收听）

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 decline noted 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.

Glossary 词汇表

species 种类 

plummeted 骤减、暴跌 

settlements 移居、定居 

journal 期刊 

trend 趋势、动向 

climate change 气候变化 

decline 下降、减少 

noted 显示、记录 

subsequently 后来、事后 

hitherto 到目前为止 

phenomenon 现象 

detect 探究、查明

Questions and Answers

What year did the number of snakes start to decline? 

1998 seems to be the year when the number of snakes in Europe, Africa and Australia started to decline.

What percentage have snake numbers fallen by in some places? 

In some places snake numbers have fallen by ninety percent in the last 15 years.

What is being suggested as a cause of this trend? 

Climate change is being suggested as a cause of the decline in snake numbers, as 1998 was a particularly hot year.

What other species has had a similar decline in numbers? 

A couple of decades ago, frogs faced a decline in numbers due to an unknown disease.