英语听力精选进阶版 7215（在线收听）

Background: 科学家们研究出一项新的方式来估计在地球上生物的总数，据统计一共有8百70万种不同类型的生物。这同过去使用的评估方式得到的结果差距很大。科学家们的发现将在网络科研期刊《生物科学公共图书馆》上发表。

It's generally accepted that very many species have yet to be discovered, but until now nobody has devised a reliable way to find out just how many. Suggestions for total numbers have ranged from 3 million to a hundred million, but most of these have been no more than intelligent guesses.

Scientists from the Census of Marine Life devised a counting method by identifying numerical patterns linking data on known species. They reckon that there should be about 8.7 million types of living organisms, three-quarters of them animals and the rest plants.

However, since the introduction of the current classification system by Carl Linnaeus in 1758, only a million and a quarter have been catalogued.

The scientists warn that human activity is hastening extinctions, and they note a touch wistfully, that many of the hitherto unknown species may vanish before we even know of their existence.

Glossary 词汇表

to devise 研究出 

reliable 可信的，可靠的 

an intelligent guess 聪明的猜测 

to reckon 估计 

a classification system 分类系统 

to catalogue 分类记载 

to hasten 加速 

wistful 愁闷的，深思的 

hitherto 迄今 

to vanish 消失

Questions:

1. What has been the estimate for the number of species? 

It has varied from 3 million to one hundred million.

2. How many living beings are animals and how many are plants?

Three-quarters are animals and one-quarter are plants.

3. What could be speeding up the extinction of some species? 

According to scientists human activity could bring about the extinction of some species.

4. True or false? Only a small number of species have been catalogued. 

True. According to the report, only a million and a quarter have been catalogued.