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
It has long been recognized that the dinosaurs disappeared from the fossil record at the end of the Cretaceous period (65 millio
It has long been recognized that the dinosaurs disappeared from the fossil record at the end of the Cretaceous period (65 millio
admin
2022-07-08
29
问题
It has long been
recognized
that the dinosaurs disappeared from the fossil record at the end of the Cretaceous period (65 million years ago), and as more knowledge has been gained, we have learned that many other organisms disappeared at about the same time. The microscopic plankton (free-floating plants and animals) with calcareous shells suffered massively. The foundation of the major marine food chain that led from the minute plankton to shelled animals to large marine reptiles had collapsed.
On land it was not only the large animals that became extinct. The mammals, most of which were small, lost some 35 percent of their species worldwide. Plants were also affected. For example, in North America 79 percent did not survive, and it has been noted that the survivors were often deciduous—they could lose their leaves and shut down—while others could survive as seeds. As in the sea, it seems that on the land one key food chain collapsed: the one with leaves as its basic raw material. These leaves were the food of some of the mammals and of the herbivorous dinosaurs, which in turn were fed on by the carnivorous dinosaurs. Furthermore, it is most likely that these large dinosaurs had slow rates of reproduction, which always increases the risk of extinction. Crocodiles, tortoises, birds, and insects seem to have been little affected. The two first named are known to be able to survive for long periods without food, and both can be scavengers. Indeed, with the deaths of so many other animals and with much dead plant material, the food chain based on detritus would have been well-supplied. Many insects feed on dead material; furthermore, most have at least one resting stage in which they are very resistant to damage. In unfavorable conditions some may take a long time to develop: there is a record of a beetle larva living in dead wood for over 40 years before becoming an adult. Some birds were scavengers, but the survival of many lineages is a puzzle.
What happened in the biological story just after these extinctions? What is found in and just above the boundary layer between the deposits of the Cretaceous and those of the Tertiary termed the K/T boundary. For a very short period the dominant microorganisms in marine deposits were usually diatoms and dinoflagellates (both single-celled types of plankton). The important feature for the survival of both these groups was the ability to form protective cysts (sacs around organisms) that rested on the sea floor. Above these, in the later deposits, are the remains of other minute plankton, but the types are quite different from those of the Late Cretaceous. In terrestrial deposits a sudden and dramatic increase in fern plant spores marks the boundary in many parts of the world; ferns are early colonizers of barren landscapes. The fern spike (sudden increase), as it is termed, has been found also in some marine deposits (such was the abundance of fern spores blown around the world), and it occurs in exactly the same layer of deposit where the plankton disappear. We can conclude that the major marine and terrestrial events occurred
simultaneously
.
Many theories have been put forward for the extinction of the dinosaurs, but most of them can be
dismissed
. In 1980, Louis Alvarez and Walter Alvarez and colleagues from the University of California published their research on the amounts of various metals in the boundary between Cretaceous and Tertiary rocks (K/T boundary) in Italy, Denmark, and New Zealand. They had found, accidentally, that a rare metal, iridium, suddenly became very abundant exactly at the boundary and then slowly fell away. This phenomenon, known as the iridium spike, has now been identified in K/T boundary deposits in over a hundred other sites in the world. Iridium occurs in meteorites and volcanic material, but in the latter case it is accompanied by
elevated
levels of nickel and chromium. These other metals are not especially abundant at the K/T boundary. The Alvarezes concluded that the iridium spike was due to a large asteroid that struck Earth 65 million years ago.
The word recognized in the first paragraph is closest in meaning to________.
选项
A、suspected
B、argued
C、assumed
D、accepted
答案
D
解析
题干recognized意为“承认(某事是事实);认识到”的意思,只有D项accepted(相信;接受)与之语义相近,故选。A项“怀疑”、B项“争论,辩论”和C项“拟定,设想”均不符合题意。
转载请注明原文地址:https://kaotiyun.com/show/lpMO777K
本试题收录于:
CATTI二级笔译综合能力题库翻译专业资格(CATTI)分类
0
CATTI二级笔译综合能力
翻译专业资格(CATTI)
相关试题推荐
Americans’MarriageandFamilyMarriageintheUnitedStatestendstolookmorelikeserialmonogamythanlifetimepartnershi
HistoryofSpecialSchoolsOneofthefirstspecialschoolsintheworldwastheInstitutNationaldesJeunesAveuglesinP
Whathappenedtothespyduringthetrial?
【L1】______and【L2】______affecthowpeoplevaluepersonalcontrolindecisionmaking,accordingtoanewstudyinBiologicalPsy
EversincetheeconomistDavidRicardoofferedthebasictheoryin1817,economicscripturehastaughtthatopentrade—freeof
Hewasfacingchargesonforgeryinacourtoflawbuthehiredagoodattorneyto______.
Shewastoldtogivetheawardtowhomsheeverthoughthadcontributedmosttothewelfareofthestudentbody.
Weactuallyfounditallworthtopreparefortheworstconditionwemightface.
EveryyearBerryBros&Rudd,Britain’soldestwinemerchant,issuesapocket-sizedpricelist.Readingoldcopiesmakesamateur
Theflagsinthestadium________inthewind.
随机试题
类风湿关节炎患者X线摄影体位中首选
不属于直接经济损失统计范围的是()。
上级机关颁布的命令,下级机关和群众必须服从,否则将受到惩戒,这体现了行政领导的()特点。
下列哪项不属于“春秋五霸”之一?()
2013年12月4日,工业和信息化部向中国移动通信集团公司、中国电信集团公司和中国联合网络通信集团有限公司颁发“LTE/()数字蜂窝移动通信业务(TD-LTE)”经营许可。
根据所给材料,回答下列问题。据说在英国人那里也出现了英语[a]的问题,或者说,英语圈内也发生了非规范化向规范化的冲击。真是“吾道不孤”——人们多以为现代汉语非规范化现象太使人生气,原来“天下乌鸦一般黑”,这[b]的恶魔到处在横行霸道。这
一个社会只有在经济增长的条件下才能对资源进行公平的分配,要想取得经济增长,该社会必须保障其每个公民的经济机会是均等的,要保障经济机会的均等就必然要求社会的政府去积极地推动它。如果上文正确,那么从中可适当地得出结论:
马克思指出:“人的本质不是单个人所固有的抽象物,在其现实性上,它是一切社会关系的总和。”这句话说明()
打开数据库的命令是
下列说法不正确的是()。
最新回复
(
0
)