雅思阅读背景知识精选.doc
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1、雅思阅读背景知识精选 今天给大家搜集了雅思阅读背景知识,一起来学习吧,下面就和大家分享,来欣赏一下吧。雅思阅读背景知识:英国人口的老龄化Ministers say people should prepare to spend more than a third of their lives in retirement due to the staggering rise in life expectancy.In the first official projection of its kind, the Department for Work and Pensions today forec
2、asts that almost a fifth of Britons will celebrate their 100th birthday.Of the 17 per cent of the population who will become centenarians, about three million are under the age of 16, and 5.5 million are aged between 16 and 50.The statistics show that there are 1.3 million 51 to 65 year-olds who are
3、 likely to get their royal telegram, along with 875,000 people who have already retired.In total, about half a million people a year will be celebrating their 100th birthday by 2066, compared with about 10,000 now. Nearly 8,000 of them will reach their 110th birthday.Last night, Steve Webb, the pens
4、ions minister, urged workers to begin saving for their retirements as soon as possible. Mr Webb is trying to introduce significant reforms to the pensions system. These staggering figures really bring home how important it is to plan ahead for our later lives, he said. Many millions of us will be sp
5、ending around a third of our lives or more in retirement.Thats why we are reforming the pension system to make it sustainable for the long term, making sure people can look forward to a decent state pension when they retire, and helping millions save into a workplace pension, many for the first time
6、.Experts said the rise in those aged over 100 years old the fastest growing age group has profound social, economic and financial implications.Taxpayers face an increasing bill to meet the pension and health care costs of the elderly.Individuals will have to work later, sell their assets and put mor
7、e money aside throughout their lives to fund retirements that could last more than 30 years.Ministers have considered linking the state pension age to life expectancy which could see future generations working into their seventies.Ros Altmann, the director-general of the Saga Group, said: Pension fu
8、nds were never designed to cater for lots of people living to 100. We have got more and more people who are going to live longer with much less money and something has to be done about it.Official research has also found that most Britons expect to die earlier than is likely to be the case.In 1981,
9、there were 2,600 centenarians but this is forecast to rise to more than 280,000 by 2050.There has already been a 70 per cent rise in people living to 100 since 2000, with six women to every man in this age group.The rich and those living in southern England typically enjoy longer lives.As people are
10、 living longer, ministers are trying to encourage workers not to opt out of new workplace pensions to be introduced next year.Most workers retire with a pension previously intended to fund a retirement of 10 or 20 years rather than an extra 30 years of life. For example, savings of 100,000 would pay
11、 out at least 5,000 a year for two decades, but less than 3,500 over three decades. Under the auto enrolment scheme, all workers will be offered a pension to which their employer will make some contributions.However, people can ask to leave the pension.The Government has previously declined to cut u
12、niversal benefits offered to pensioners and will increase the state pension in line with wages, rather than inflation, from next year.Some experts believe that such measures will become increasingly unfair on younger generations.Life expectancy for babies and those retiring has confounded experts, r
13、ising more quickly than expected.Average life expectancy for a newborn girl is now 81 years and nine months, while for boys it is 77 years and seven months.More than a quarter of newborn boys 30 years ago were expected to die before their 65th birthday, compared with 15 per cent today雅思阅读背景知识之地质学篇地质
14、学(geology)是关于地球的物质组成、内部构造、外部特征、各层圈之间的相互作用和演变历史的知识体系,是研究地球本身的学科。需要与之区分的是地理学(geography),是一门描述地球表面的科学。地理学描述和分析发生在地球表面上的自然、生物和人文现象的空间变化,探讨它们之间的相互关系及其重要的区域类型。相信广大考生应该还记得中学时学过,地球的内部结构是一个同心状圈层构造,由地心至地表依次分化为地核 (core)、地幔(mantle)、地壳(crust)。地球地核、地幔和地壳的分界面,主要依据地震波(seismic/earthquake wave)传播速度的急剧变化推测确定。如果把地球内部结构
15、做个形象的比喻,它就像一个鸡蛋,地核就相当于蛋黄,地幔就相当于蛋白,地壳就相当于蛋壳。从地球的外部结构来看,则可以分成大气圈(atmosphere)、水圈(hydrosphere)、生物圈(biosphere)和岩石圈 (lithosphere),岩石圈包括地壳和地幔上部。地球上有七大洲和五大洋,分别是亚洲(Asia),欧洲(Europe),北美洲(North America),南美洲(South America),非洲(Africa),大洋洲(Oceania)和南极洲(Antarctica);太平洋(Pacific Ocean),大西洋(Atlantic Ocean),印度洋(Indian
16、Ocean),北冰洋(Arctic Ocean)和南冰洋(Antarctic Ocean)。大陆漂移学说(Continental Drift)大陆漂移学说是有关于地球大陆之间关系的一种假说(hypothesis)。早在1596年,亚伯拉罕奥特柳思(Abraham Ortelius)首次提出了这个观点,而对于这个观点我们比较熟悉的则是阿尔弗雷德魏格纳(Alfred Wegener),他于1912年相对完整地提出了这套假说。到了二十世纪六十年代,随着板块构造学说(Plate Tectonics)的发展,大陆漂移学说得到了更多的支持。如果仔细观察一下世界地图,我们会发现非洲和南美洲的海岸线似乎能像拼
17、图一样吻合在一起,早期的科学家们正是发现了这一点,才最终提出了大陆漂移学说。魏格纳提出在中生代(Mesozoic)地球表面存在一个泛大陆 (Pangea),这个超级大陆经过了分裂和两亿多年的漂移形成了现在的海洋和陆地。除了非洲和南美洲海岸线的“锯齿状吻合”,还有很多其他的证据能支持大陆漂移这个观点。魏格纳在研究古代气候的时候发现,各个大陆上存在某一个地质时期形成岩石类型出现在现代条件下不该出现的地区。例如,在南极洲地区出现古珊瑚礁(coral reef)和热带植物(tropical plants)化石(fossil);在赤道(equator)地区发现有古代冰层。魏格纳还认为,大陆漂移对现代由海
18、洋分隔的各大陆上动物和植物的显著相似性提供了最好的解释。例如中龙(mesosaurus)这种淡水爬行类动物(reptile),在南美和非洲都能找到;存在于南极洲三叠纪 (Triassic period)有许多陆生爬行动物的化石在其他大陆同样存在。板块构造学(Plate Tectonics)板块构造学说以大陆漂移学说为基础,主要描述了地球岩石圈(lithosphere)的大范围运动。在二十世纪五十年代末六十年代初,海底扩张学说 (Seafloor Spreading)发展起来了,大陆漂移学说也因此变得更为可信。1968年法国地质学家勒皮雄和麦肯锡、摩根等人提出了板块构造学说,作为一种新的大陆漂移
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