首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The human species came into being at the time of the greatest biological diversity in the history of the Earth. Today, as human
The human species came into being at the time of the greatest biological diversity in the history of the Earth. Today, as human
admin
2015-06-27
74
问题
The human species came into being at the time of the greatest biological diversity in the history of the Earth. Today, as human populations expand and alter the natural environment, they are reducing biological diversity to its lowest level. The ultimate consequences of this biological reduction are beyond calculation, but they are certain to be harmful. That, in essence, is the biodiversity crisis.
The history of global diversity can be summarized as follows: after the initial flowering of multicellular animals, there was a swift rise in the number of species in early Paleozoic times (between 600 and 430 million years ago), then plate-alike stagnation for the remaining 200 million years of the Paleozoic era, and finally a slow but steady climb through the Mesozoic and Cenozoic eras to diversity’s all-time high. This history suggests that biological diversity was hard won and a long time in coming. Furthermore, this pattern of increase was set back by five massive extinction episodes. The most recent of these, during the Cretaceous period, is by far the most famous, because it ended the age of the dinosaurs, giving hegemony to the mammals, thus ultimately making possible the dominance of the human species over the Earth. But the Cretaceous crisis was minor compared with the Permian extinctions 240 million years ago, during which between 77 and 96 percent of marine animal species perished. It took five million years, well into Mesozoic times, for species diversity to begin a significant recovery.
Within the past 10,000 years biological diversity has entered a wholly new era. Human activity has had a devastating effect on species diversity, and the rate of human-induced extinctions is accelerating. Half of the bird species of Polynesia have been eliminated through hunting and the destruction of native forests. The list of such biogeographic disasters is extensive.
Because every species is unique and irreplaceable, the loss of biodiversity is the most profound process of environmental change. Its consequences are also the least predictable because the value of the Earth’s species remains largely unstudied and unappreciated; unlike material and cultural wealth, which we understand because they are the substance of our everyday lives, biological wealth is usually taken for granted. This is a serious strategic error, one that will be increasingly regretted as time passes.
All of the following contribute to the extinction of species EXCEPT
选项
A、hunting.
B、pollution.
C、deforestation.
D、the growth of human populations.
答案
B
解析
由第三段第三句“在波利尼西亚,有一半的鸟类由于人类捕猎或者当地森林被破坏而消失的”可排除[A]和[C];而根据第一段第二句“人类人口的不断增长以及对自然环境的改变,使物种数量降低到最低水平”可排除[D],因此答案为[B]。
转载请注明原文地址:https://kaotiyun.com/show/ZHXK777K
0
专业英语四级
相关试题推荐
TheChinesefilmsuperstaroncesaidthathewouldrather______rememberedasacommonpersonthanasacelebrity.
ThegenerationofAmericanswhoarenow(in1989)youngadultshasbeen,asoddasitsounds,deprivedoftheadversitythathas
Thelocalgovernmenthasto______thetaxschemebecauseofthestrongopposition.
Ofallthegoalsoftheeducationreformmovement,noneismoredifficultthandevelopinganobjectivemethodtoassessteachers
Theman’sefforttofindapositiondoesnotinclude_______.
WriteonANSWERSHEETTWOacompositionof200wordsonthefollowingtopic:TheImportanceofWaterResource
Advertiserstendtothinkbigandperhapsthisiswhythey’realwayscominginforcriticism.Theircriticsseemtoresentthem
Itissowarmand______bythefirethatIfeellikesleeping.
Moreimportanceneedstobegiventosports,andacarefulchoiceof______formsaremostsuitableshouldbemade;thiscallsfor
Thenewsitemismainlyaboutthebackgroundof
随机试题
简述管理信息系统的功能。
结肠带、结肠袋和肠脂垂作为特征性结构,通常存在于()
A.流感杆菌B.副流感病毒C.流感病毒D.溶血性链球菌E.柯萨奇病毒急性会厌炎常见致病菌是
急性血源性骨髓炎,在X线片上出现异常的时间为起病后
下列各项中,属于会计软件取得方式的有()。
某企业7月份发生一笔经济业务,购进不需安装的固定资产,原价为100万元,不考虑增值税,则丁字账户中,()。
下列哪一项表述符合公示催告程序的法律规定?()
使用操作系统提供的()接口,能在用户程序中将一个字符送到显示器上显示。
Incomputerprogramming,thismodelis______toanyoftheotherswehaveeverhad.
A、 B、 C、 B
最新回复
(
0
)