请jcz2008进来看一下

jcz2008

Black bears feed on leaves, herbs. Fruit, berries, insects, fish, and
even larger animals. One of the most interesting characteristics of
bears, including the black bear, is their winter sleep. Unlike
squirrels, woodchucks, and many other woodland animals, bears do not
actually hibernate. Although the bear does not during the winter moths,
sustaining itself from body fat, its temperature remains almost normal,
and it breathes regularly four or five times per minute.
Most black bears live alone, except during mating season. They prefer to
live in caves, hollow logs, or dense thickets. A little of one to four
cubs is born in January or February after a gestation period of six to
nine months, and they remain with their mother until they are fully
grown or about one and a half years old. Black bears can live as long as
thirty years in the wild , and even longer in game preserves set aside
for them.

曾经沧海难为水

谢谢哥们了！天涯无路情当桥，四海为家共荣华。

曾经沧海难为水

谢谢！无私的帮助！

lighting2003

我倒，更新了也不通知一声，我要继续加，^_^。希望能背下来几句经典名言，打动ETS哪些机器的心。

lighting2003

对了，那个什么常青藤的托福单词是什么啊，有的化给大家发个别。

jcz2008

hehe 那是一本单词书,像砖头一样的, 世界图书出版社的, 根据最新托福考试机检高频词汇编写的,  我觉得那本比较全面一点吧!  

jcz2008

41.American black bears
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 brown and black furred bears may be
born.
Black bears are the smallest of all American bears, ranging in length
from five to six feet, weighing from three hundred to five hundred
pounds Their eyes and ears are small and their eyesight and hearing are
not as good as their sense of smell.
Like all bears, the black bear is timid, clumsy, and rarely dangerous ,
but if attacked, most can climb trees and cover ground at great speeds.
When angry or frightened, it is a formidable enemy.
Black bears feed on leaves, herbs. Fruit, berries, insects, fish, and
even larger animals. One of the most interesting characteristics of
bears, including the black bear, is their winter sleep. Unlike
squirrels, woodchucks, and many other woodland animals, bears do not
actually hibernate. Although the bear does not during the winter moths,
sustaining itself from body fat, its temperature remains almost normal,
and it breathes regularly four or five times per minute.
Most black bears live alone, except during mating season. They prefer to
live in caves, hollow logs, or dense thickets. A little of one to four
cubs is born in January or February after a gestation period of six to
nine months, and they remain with their mother until they are fully
grown or about one and a half years old. Black bears can live as long as
thirty years in the wild , and even longer in game preserves set aside
for them.

jcz2008

42.Coal-fired power plants
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 stations. (which were set up at the end
of the nineteenth century by Edison himself). As more power plants were
constructed throughout the country, the reliance on coal increased
throughout the country, the reliance on coal increased. Since the First
World War, coal-fired power plants had a combined in the United States
each year. In 1986 such plants had a combined generating capacity of
289,000 megawatts and consumed 83 percent of the nearly 900 million tons
of coal mined in the country that year. Given the uncertainty in the
future growth of the nearly 900 million tons of coal mined in the
country that year. Given the uncertainty in the future growth of nuclear
power and in the supply of oil and natural gas, coal-fired power plants
could well provide up to 70 percent of the electric power in the United
States by the end of the century.
Yet, in spite of the fact that coal has long been a source of
electricity and may remain on for many years(coal represents about 80
percent of United States fossil-fuel reserves), it has actually never
been the most desirable fossil fuel for power plants. Coal contains less
energy per unit of weight than weight than natural gas or oil; it is
difficult to transport, and it is associated with a host of
environmental issues, among them acid rain. Since the late 1960’s
problems of emission control and waste disposal have sharply reduced the
appeal of coal-fired power plants. The cost of ameliorating these
environment problems along with the rising cost of building a facility
as large and complex as a coal-fired power plant, have also made such
plants less attractive from a purely economic perspective.
Changes in the technological base of coal-fired power plants could
restore their attractiveness, however. Whereas some of these changes are
intended mainly to increase the productivity of existing plants,
completely new technologies for burning coal cleanly are also being
developed.

jcz2008

43.Statistics
There were two widely divergent influences on the early development of
statistical methods. Statistics had a mother who was dedicated to
keeping orderly records of government units (states and statistics come
from the same Latin root status) and a gentlemanly gambling father who
relied on mathematics to increase his skill at playing the odds in games
of chance. The influence of the mother on the offspring, statistics, is
represented by counting, measuring, describing, tabulating, ordering,
and the taking of censuses-all of which led to modern descriptive
statistics. From the influence of the father came modern inferential
statistics, which is based squarely on theories of probability.
Describing collections involves tabulating, depicting and describing
collections of data. These data may be quantitative such as measures of
height, intelligence or grade level------variables that are
characterized by an underlying continuum---or the data may represent
qualitative variables, such as sex, college major or personality type.
Large masses of data must generally undergo a process of summarization
or reduction before they are comprehensible. Descriptive statistics is a
tool for describing or summarizing or reducing to comprehensible form
the properties of an otherwise unwieldy mass of data.
Inferential statistics is a formalized body of methods for solving
another class of problems that present great of problems
characteristically involves attempts to make predictions using a sample
of observations. For example, a school superintendent wishes to
determine the proportion of children in a large school system who come
to school without breakfast, have been vaccinated for flu, or whatever.
Having a little knowledge of statistics, the superintendent would know
that it is unnecessary and inefficient to question each child: the
proportion for the sample of as few as 100 children. Thus , the purpose
of inferential statistics is to predict or estimate characteristics of a
population from a knowledge of the characteristics of only a sample of
the population.

飘零纷雪

是谁这么伟大，爱死你了