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
An epidemic of swine flu (猪流感) has recently developed in Mexico and the United States, says the CDC. Swine flu has killed many p
An epidemic of swine flu (猪流感) has recently developed in Mexico and the United States, says the CDC. Swine flu has killed many p
admin
2011-04-04
80
问题
An epidemic of swine flu (猪流感) has recently developed in Mexico and the United States, says the CDC. Swine flu has killed many people, and the outbreak has features that suggest it could become a global pandemic (瘟疫). A pandemic is an epidemic that spreads around the whole world. Pandemics also often cause more severe disease than epidemics.
Flu is a disease caused by the influenza virus. Humans, pigs, birds and other animals all can be infected by influenza viruses. Typically, influenza viruses can infect only one species, so the influenza viruses of humans are different from those of pigs and birds. However, sometimes a virus can infect more than one species. For examples, pigs sometimes can be infected not only with pig influenza viruses, but also with human and bird influenza viruses. Then these viruses can come up to one another secretly and swap (交换) genes, creating new viruses that have a mix of genes -- from human, pig, and bird viruses. That is what has happened with this new swine flu virus.
Sometimes this swapping of genes allows a virus that was originally able to infect only pigs or only birds to also infect humans. When that happens, we refer to the illness as "swine flu" or "bird flu". This current virus could actually be called "swine/bird flu", since it has some genes from pig flu viruses and other genes from bird flu viruses.
Most viruses that cause swine flu or bird flu are very hard to pass from one human to another: they don’t cause epidemics. Sometimes, however, further changes in genes create a virus that can spread rapidly among humans, and can produce a more severe illness. One reason this illness is more severe is that the virus is so new. The regular flu that comes each year is caused by a regular human influenza virus that often has similarities to the viruses that have caused the flu in years past, so people have some degree of immunity to the latest virus. The unusual swine flu or bird flu viruses that develop the ability for person-to-person spread are so different that people have little or no immunity to them.
The worst global pandemic in modem times was the influenza pandemic of 1918 to 1919. It affected about a third of the human race, and killed at least 40 million people in less than a year -- more than those who have been killed by AIDS in three decades. The world economy went into a deep recession. The average length of life dropped for 10 years.
Unfortunately, the new swine flu virus can be transmitted between humans. It is not clear yet how easily it is transmitted, nor how it is transmitted. Almost surely it is transmitted by sneezing and coughing, and by skin-to-skin contact with an infected person.
Which of the following is true about the present swine flu viruses?
选项
A、The viruses can infect different species.
B、The genes of the viruses come from pigs.
C、The viruses mix genes from different species.
D、The genes of the viruses were made artificially.
答案
A
解析
题干问的是目前的猪流感病毒的情况。原文从第二段开始对这种新流感病毒分析描述。第三句说,通常情况下,流感病毒只感染一个物种。第四句说,有时一种病毒却可能感染多个物种。然后举例,最后一句说这次的新型猪流感病毒就属于这种情况。由后文也可知道,这种新型猪流感病毒能感染人、猪和鸟类。所以[A]项正确。
转载请注明原文地址:https://kaotiyun.com/show/kMo7777K
0
大学英语六级
相关试题推荐
A、Heshouldn’thaveapologized.B、Hewillfindabetterwayofapologizing.C、Hecouldn’tfindarightwordtomakeanapology.
Beijing2008:TheFirst4GWirelessOlympicGames?Abouthalfamillionyearsago,PekingmanlivedinZhoukoudian,inthe
A、Sunlight.B、Location.C、Soil.D、Drainage.C信息明示题。女士在介绍如何进行平方英尺园艺时,提到了选择好的位置,即选择每天可直接接受日晒6~8小时、排水性好、方便的位置,由此可排除A、B、D,故选c。
Ironically,intheUnitedStates,acountryofimmigrants,prejudiceanddiscriminationcontinuetobeseriousproblems.Therew
A、Romanticlighting,B、Fantasticmusic.C、Amazingcostumes.D、Animalperformers.D信息明示题。女士说太阳剧团的风格是其他马戏团所没有的.包括柔和、浪漫的灯光,从古典音乐到爵士
Areyouworriedabouttherisingcrimerate?Ifyonare,thenyouprobablyknowthatyourhouse,possessionsandpersonsareinc
A、Two.B、Three.C、Four.D、Five.C信息明示题。文章第三段通过问题whatarethespecifictraitsthatwillhelppeopletoclimbtheladderofsucces
Jazzhasbeencalled"theartofexpressionsettomusic".Ithasfunctionedaspopularartandenjoyedperiodsoffairly【B1】____
A、Thelibraryiswithinwalkingdistance.B、Thestreetsarenotingoodcondition.C、Themanshouldgetacarinstead.D、Theman
A、Theyrelyheavilyontheirownimagination.B、Theyhaveexperiencessimilartothecharacters’.C、Theylookattheworldina
随机试题
()油井生产压差越大,单井产量越低,反之则上升。
(2015年第4题)下列情况下,能使红细胞渗透脆性增高的是
依照法律规定剥夺犯罪人某种权益的强制方法是
以下关于室内污染物氡叙述正确的是()。
根据《水电建设工程质量管理暂行办法》,()负责向质监总站报告工程质量工作。
生产烟花爆竹的企业在申请出口烟花爆竹的检验时,可不必提交的材料有( )。
根据《个人独资企业法》规定,投资人违法经营并造成他人损害的,其财产不足以支付罚款和赔偿损失肘,应( )。
世界遗产是指被联合国教科文组织和世界遗产委员会确认的人类罕见的、目前无法替代的财富,是全人类公认的具有突出意义和普遍价值的文物古迹及自然景观。下列哪一项属于中国的世界文化、自然双重遗产?()
Therecentwarmtrendwillend______tonightasacoldfrontdropsinfromthenorth,justintimefortheweekend.
A、Britneyisnotasbeautifulassheusedtobe.B、Heregretspayingfortheconcert.C、Theconcertsareunsatisfactory.D、Britn
最新回复
(
0
)