Question

There might be as many as 10 million species of complex life on this planet today —— a huge number. But add up all of the complex species that ever lived and some biologists think the grand total would be about five billion. The estimate leads to an astonishing conclusion: a staggering 99% of species are not around any more. They have been driven to extinction.

More species are joining the ranks of the extinct every year. Many scientists believe we are living through an episode of remarkably rapid extinction, on a scale that has been seen only five times in the last half a billion years.

They call this current episode the sixth mass extinction —— a large, global decline in a wide variety of species over a relatively short period of time. And they tend to agree that humans are the main cause.

Over-hunting, overfishing, and human-driven habitat loss are pushing many species to the brink. In fact, we have changed the planet so much that some geologists are now suggesting that we have entered a new phase in Earth’s history; an epoch they call the ＂Anthropocene＂. By 2100, it is expected that humans will have caused the extinction of up to half of the world’s current species.

Because we are living through this extinction, it is relatively easy for us to study the driving forces behind it. But how do we determine what caused other mass die-offs that happened long ago? To do so we have to look at what archaeologists, palaeontologists, geologists and other scientists have concluded from the evidence they have gathered.

The trouble is, those scientists do not always agree with one another —— even about the most recent extinction event. As well as the five-or six- mass extinctions, there have also been many smaller extinctions.

One of these mini extinction events happened towards the end of the Pleistocene, a few tens of thousands of years ago. It is sometimes called the ＂megafaunal＂ extinction because many of the species it claimed were particularly large animals, weighing more than 97lb (44kg). However, its cause remains a debate amongst scientists.

1.What can we learn about the sixth mass extinction？

A. Humans are the main cause of it.

B. It means a global decline over a long time.

C. It occurred towards the end of the Pleistocene.

D. Scientists still disagree about the cause of it.

2.What can be inferred from the text about species？

A. 99% of species will not be around any more by 2100.

B. By the 22nd century, there will probably be about five million on this planet.

C. About eight years later we will enter what is called the ＂Anthropocene＂.

D. It is not easy for us to figure out causes behind the＂Anthropocene＂.

3.Which of the following is closest in meaning to the underlined word in the last paragraph ?

A. Land animals.    B. Marine life.

C. Huge animals.    D. Flesh-eating creatures.

Answer

1.A

2.B

3.C

【解析】本篇探讨的话题是关于一些物种灭绝的原因。目前地球上生物大约有1000万种，而曾经生活在地球上的物种多达50亿，也就是说其中百分之九十九的生物已经灭绝了。许多科学家认为，我们正经历着地球史上第六次大规模物种灭绝，而且他们倾向于认为人类的过度捕猎、过度捕捞和人类栖息地的丧失是主要的原因。因为我们正在经历这种灭绝，所以研究其背后的原因是相对容易的。但是，各个科学家对过去物种灭绝原因有着不同的看法，即便是最近的一次小规模物种灭绝——大型动物灭绝，有关的灭绝原因，科学家仍在争论。

1.细节理解题。第三段提到大规模物种灭绝是在a relatively short period of time，所以B项错误；最后一段提到大型动物的灭绝发生在the end of the Pleistocene，而第六次大规模物种灭绝是当下正在发生的，所以C项错误；根据第三段＂They call this current episode the sixth mass extinction —— a large, global decline in a wide variety of species over a relatively short period of time. And they tend to agree that humans are the main cause.＂可知，科学家认为人类是第六次大规模物种灭绝的主要原因，没有不同意见，因此D项错误，A项正确。

2.推理判断题。根据第一段最后一句＂a staggering 99% of species are not around any more.＂可知，目前地球上已经有99%的物种灭绝了，不用等到2100年，所以A项错误；根据第四段“In fact, we have changed the planet so much that some geologists are now suggesting that we have entered a new phase in Earth’s history; an epoch they call the ＂Anthropocene＂.”可知，我们现在已经进入了＂Anthropocene＂时代，而非8年后，所以C项错误；同样根据前句可知，科学家认为我们现在已经进入＂Anthropocene＂时代的原因是we have changed the planet so much，原因很明确，所以D项错误；根据文章第一句话“There might be as many as 10 million species of complex life on this planet today ”，以及第四段中的＂By 2100, it is expected that humans will have caused the extinction of up to half of the world’s current species.＂可知，到22世纪，地球还会有目前物种的1/2会灭绝，也就是10million的半，即five million，因此B项正确。

3.词义猜测题。由下文对该词的解释＂because many of the species it claimed were particularly large animals, weighing more than 97lb (44kg).＂可推知 ＂megafaunal＂应为大型动物，因此C项正确。