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
Generally, in order to be preserved in the fossil record, organisms must possess hard body parts such as shells or b
Generally, in order to be preserved in the fossil record, organisms must possess hard body parts such as shells or b
admin
2004-12-30
41
问题
Generally, in order to be preserved in the fossil record, organisms must possess hard body parts
such as shells or bones. Soft, fleshy structures are quickly destroyed by predators pr decayed by
bacteria. Even hard parts left on the surface for and length of time will be destroyed Therefore,
organisms must be buried rapidly to escape destruction by the elements and to be protected
(5) agents of weathering and erosion Marine organisms thus are better candidates for
fossilization than those living on the land because the ocean is typically the site of sedimentation,
whereas the land is largely the site of erosion.
The beds of ancient lakes were also excellent sites for rapid burial of skeletal remains of
freshwater organisms and skeletons of other animals, including those of early humans Ancient
(10) swamps were particularly plentiful with prolific growths of vegetation, which fossilized in
abundance. Many animals became trapped in bogs overgrown by vegetation. The environment of
the swamps kept bacterial decay to a minimum, which greatly (aide(D)in the preservation of plants
and animals. The rapidly accumulating sediments in flood plains, deltas, and stream channels
buried freshwater organisms, along with other plants and animals that happened to fall into the
(15) water.
Only a small fraction of all the organisms that have ever lived are preserved as fossils. Normally,
the remains of a plant or animal are completely destroyed through predation and decay. Although
it seems that fossilization is common for some organisms, for others it is almost impossible. For
the most part, the remains of organisms are recycled in the earth, which is fortunate because
(20) otherwise soil and water would soon become depieted of essential nutrients. Also, most of the
fossils exposed on Earth’s surface are destroyed by weathering processes. This makes for an
incomplete fossil record with poor or no representation of certain species.
The best fossils are those composed of unaltered remains. Generally, it is the inorganic hard parts,
composed mostly of calcium carbonate, that form the vast majority of unaltered fossils. Calcite and
(25) aragonite also contributed to a substantial number of fossils of certain organisms.
选项
A、is not likely to appear in the fossil record
B、is not heavy enough to sink below the surface
C、is not attractive to predators
D、takes a long time to decay
答案
A
解析
转载请注明原文地址:https://jikaoti.com/ti/5FAYFFFM
0
托福(TOEFL)
相关试题推荐
DothefollowingstatementsagreewiththeinformationgiveninReadingPassage3?Inboxes37-40onyouranswersheet,writeTR
Thepassageendsbynotingthatourviewofhistoryisbiasedbecause
Completethesummarybelow.ChooseONEWORDONLYfromthepassageforeachanswer.Writeyouranswersinboxes24-26onyourans
Completethesummarybelow.ChooseONEWORDONLYfromthepassageforeachanswer.Writeyouranswersinboxes24-26onyourans
Lookatthefollowingfindings(Questions20-23)andthelistofresearchersbelow.Matcheachfindingwiththecorrectresearch
Youshouldspendabout20minutesonQuestions14-26whicharebasedonReadingPassage2below.Youngchild
Completethenotesbelow.ChooseONEWORDfromthepassageforeachanswer.Writeyouranswersinboxes7-13onyouranswershee
Completethenotesbelow.ChooseONEWORDfromthepassageforeachanswer.Writeyouranswersinboxes7-13onyouranswershee
Labelthemapbelow.Writethecorrectletter,A-H,nexttoquestions16-20.MedicalRecordsOffice
Choosethecorrectletter,A,BorC.Wheredidthestudentsrecordtheirsourcesofinformation?
随机试题
设二维随机变量(X,Y)的分布函数为F(x,y),则P{X≤0,Y≤0}用F(x,y)表示为________.
患者,男,20岁,右大腿刀刺伤18小时,刀口处红肿,有渗出液,目前最适当的治疗措施是
【2012年第4题】题11~15:某企业10kV变电所,装有容量为20MVA的主变压器两台。2回110kV出线(GIS),10kV母线为单母线分段接线方式,每段母线均有15回馈线。值班室设置变电所监控系统,有人值班。请回答以下问题,并列出解答过程。若变
下列命题正确的是:
根据《建筑地基处理技术规范》JGJ79—2012,下列地基处理的做法中,不正确的是()。
按照中国证监会2007年3月的最新规定,开放式基金认(申)购费率将统一按净认购金额为基础收取。()
人民警察职业道德三个最显著的特征是鲜明的阶级性、广泛的人民性和()。
某天夜里,甲喝酒后走路回家,发现前面走着一位年轻漂亮的姑娘乙,乙单身一个人,没有人陪伴。甲色心骤起,用刀将乙逼至一个僻静的小巷,欲行强奸。乙拼命反抗,为了压制乙的反抗,甲将乙打晕后进行强奸。强奸完后,甲发现乙还未醒来,于是将乙随身携带的钱包和手机拿走,价值
在窗体中放置控件,对该控件的操作错误的是()。
【B1】【B7】
最新回复
(
0
)