Question

Birds enjoy a relatively slow rate of extinction but a new study suggests that rate might be severely underestimated(低估). Even worse, if human actions continue, bird extinction rates could skyrocket and 12 percent of the known bird species(物种) could be dying out by the end of the century.

Presently there are 10,000 known bird species — most identified after 1850 — and an estimated 130 of those have become extinct since 1500, setting the extinction rate at about one species every four years.

But according to Stuart Pimm of Duke University, this rate fails to take into account three key points: The continual identification of extinct bird species from fossil remains; numerous "missing" species not yet declared extinct; and the fact that present extinction rates were not calculated using the proper baseline date for when the species was first described.

Taking these points into consideration, the extinction rate is closer to one bird species per year, says Pimm, the leading author of the study. And the rate could be three times as high as that if not for recent bird preservation efforts.

In previous centuries, bird extinctions took place mainly on islands as Polynesian peoples expanded into the Pacific or Europeans took over the Americas, wiping out birds along the way.

In recent years, scientists are seeing an increased number of extinctions on continents, again because of human activities. Habitat destruction, introduction of invasive species, and climate change combine to harm many bird species. Before human influence, the estimated rate of bird extinctions would have been only one species per hundred years, researchers estimate.

Bird extinction rates are slower than for most animals, mainly because humans do more harm to other species and people take special efforts to protect birds. Still, if the present trends continue, the researchers estimate that the bird extinction rate will continue to climb to as many as 10 species per year,

1.The underlined word "skyrocket" in the first paragraph means

A. fly high

B. appear soon

C. increase quickly

D. change regularly

2.According to Pimm, the extinction rate of birds is____________.

A. one species per hundred years

B. one species every year

C. three species per year

D. ten species every year

3.What can we infer from the fifth and sixth paragraphs?

A. Humans have started destroying bird habitat in recent years.

B. Humans are doing more harm to animals than to birds.

C. Humans have made no effort to protect birds.

D. Humans are responsible for the bird extinctions.

4.What might be the best title for the passage?

A. Humans' Fighting against Bird Extinction

B. Humans' Responsibilities for Bird Protection

C. Bird Extinction Rates Far Worse Than Realized

D. Bird Extinction Occurring on Islands and Continents

Answer

1.C

2.B

3.D

4.C

【解析】

本文是说明文。讲述了鸟类灭绝现状的严重性，分析了导致此现状的原因。

1.猜测词义题。句意：更糟糕的是，如果人类活动继续,鸟灭绝率可能飙升，12%的已知鸟类可能到本世纪末灭绝。根据第二段中and an estimated 130 of those have become extinct since 1500, setting the extinction rate at about one species every four years.可知从1500年来已经有130中已经灭绝，灭亡率是大约每四年一种。第四段the extinction rate is closer to one bird species per year, ……And the rate could be three times as high as that……可知现在灭亡率接近每年一种，以后还可能会高达现在的三倍。由这些数据可知"skyrocket"指的是飞涨，飙升，与increase quickly同义，故选C。

2.细节理解题。根据第四段Taking these points into consideration, the extinction rate is closer to one bird species per year, says Pimm,可知Pimm认为鸟类每年的灭绝率接近一种，故选B。

3.推理判断题。根据第五段中……Polynesian peoples expanded into the Pacific or Europeans took over the Americas, wiping out birds along the way.第六段中an increased number of extinctions on continents, again because of human activities.及人类影响前后鸟类灭绝的对比可知，这两段告诉我们人类的行为造成了鸟类灭绝，应该为此负责。故选D。

4.标题判断题。根据首段Birds enjoy a relatively slow rate of extinction but a new study suggests that rate might be severely underestimated.和下文对鸟类灭绝的现状及原因分析可知，本文主要讲述的是鸟类灭绝的严重情况，不是讲述人类的保护。C项Bird Extinction Rates Far Worse Than Realized鸟类的灭绝率远比意识到的要糟糕，既能概括全文又能吸引读者，适合作为标题。故选C。