The preservation of embryos and juveniles is a rate occurrence in the fossil record. The tiny, delicate skeletons are usually scattered by scavengers or destroyed by weathering before they can be fossilized. Ichthyosaurs had a higher chance of being

发表于:2018-12-04 / 阅读(56) / 评论(0) 分类 考研背诵50篇

In science, a theory is a reasonable explanation of observed events that are related. A theory often involves an imaginary model that helps scientists picture the way an observed event could be produced. A good example of this is found in the kinetic

发表于:2018-12-04 / 阅读(48) / 评论(0) 分类 考研背诵50篇

Television has become the main source of informatio [00:03.84]and entertaiment for the average America [00:07.97]It is estimated that by the time a child reaches 1 [00:12.64]he or she has spent almost twice as much time watching TV as in the classroo

发表于:2018-12-04 / 阅读(142) / 评论(0) 分类 考研英语听力基本功4

Have you ever considered sky divin [00:03.08]Thousands of people learn to sky dive each yea [00:06.82]The first major step to learn is proper touch down techniqu [00:11.57]That means learning how to fall properly,initially from a four-foot platfor [0

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Children don't know which things are dangerou [00:03.21]Keeping a constant eye on them as they move around is very difficul [00:08.39]You can't be everywhere at once,and anyway it's important for them to learn about the world around the [00:15.23]But

发表于:2018-12-04 / 阅读(126) / 评论(0) 分类 考研英语听力基本功4

Franklin D Roosevelt was elected Presiden [00:16.12]in November 193 [00:26.98]When he took the presidential oat [00:38.14]the banking and credit system of the nati [00:54.33]was in a state of paralysi [01:05.49]The new preside [01:12.49]brought an ai

发表于:2018-12-04 / 阅读(109) / 评论(0) 分类 考研英语听力基本功1

I remember just how it was that da [00:13.95]the first hint of spring floated across the rive [00:31.37]mixing with the coal smoke from the factorie [00:47.07]As I turned the corner on my way to wor [01:01.13]and came to the toy stor [01:11.31]I thou

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Many people have criticized television programmin [00:18.39]They complain that it does not challenge the intellec [00:37.59]shows too much violenc [00:47.44]and appeals to the least educated of viewer [01:04.86]in order to get the largest audienc [01

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The majority of fish live in shallow parts of the se [00:19.88]Fish are varied but they have certain common feature [00:40.46]Fins are special organs which help the fish to swim in wate [01:03.03]They can help the fish to stea [01:15.57]and steer its

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Today I'd like to introduce the new technology,e-mai [00:22.65]The most widely used tool on the Internet is electronic mai [00:45.56]or e-mai [00:50.76]E-mail is used to send written messages between individual [01:13.14]or groups of individual [01:2

发表于:2018-12-04 / 阅读(111) / 评论(0) 分类 考研英语听力基本功1

Cells cannot remain alive outside certain limits of temperature and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only within a narrow range around 37C; a departure of a few

发表于:2018-12-30 / 阅读(62) / 评论(0) 分类 考研背诵50篇

American black bears appear in a variety of colors despite their name. In the eastern part of their range, most of these brown, red, or even yellow coats. To the north, the black bear is actually gray or white in color. Even in the same litter, both

发表于:2018-12-30 / 阅读(58) / 评论(0) 分类 考研背诵50篇

The invention of the incandescent light bulb by Thomas A. Edison in 1879 created a demand for a cheap, readily available fuel with which to generate large amounts of electric power. Coal seemed to fit the bill, and it fueled the earliest power statio

发表于:2018-12-30 / 阅读(67) / 评论(0) 分类 考研背诵50篇

British Columbia is the third largest Canadian provinces, both in area and population. It is nearly 1.5 times as large as Texas , and extends 800 miles( 1,280km ) north from the United States border. It includes Canada s entire west coast and the isl

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Atmospheric pressure can support a column of water up to 10 meters high. But plants can move water much higher; the sequoia tree can pump water to its very top more than 100 meters above the ground. Until the end of the nineteenth century, the moveme

发表于:2018-12-30 / 阅读(98) / 评论(0) 分类 考研背诵50篇

The theory of plate tectonics describes the motions of the lithosphere, the comparatively rigid outer layer of the Earth that includes all the crust and part of the underlying mantle. The lithosphere(n.[ 地 ] 岩石圈 )is divided into a few dozen p

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The increase in international business and in foreign investment has created a need for executives with knowledge of foreign languages and skills in cross-cultural communication. Americans, however, have not been well trained in either area and, cons

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Accustomed though we are to speaking of the films made before 1927 as silent, the film has never been, in the full sense of the word, silent. From the very beginning, music was regarded as an indispensable accompaniment; when the Lumiere films were s

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When you first arrive in the U.S. [00:12.83]you will be given the name and telephone extension numb [00:30.38]of the officer who will be administering your programm [00:49.55]It will be helpful if you make a note in your dia [01:08.00]of this informa

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The first true piece of sports equipment that man invente [00:21.71]was the bal [00:35.60]In ancient Egypt,as everywher [00:49.50]pitching stones was a favorite children's gam [01:05.59]But a badly thrown rock could hurt a child. [01:23.17]Looking fo

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