Sleep is very ancient. In the electroencephalographic sense we share it with all the primates and almost all the other mammals and birds: it may extend back as far as the reptiles.
There is some evidence that the two types of sleep, dreaming and dreamless, depend on the life-style of the animal, and that predators are statistically much more likely to dream than prey, which are in turn much more likely to experience dreamless sleep. In dream sleep, the animal is powerfully immobilized and remarkably unresponsive to external stimuli.
Dreamless sleep is much shallower, and we have all witnessed cats or dogs cocking their ears to a sound when apparently fast asleep. The fact that deep dream sleep is rare among prey today seems clearly to be a product of natural selection, and it makes sense that today, when sleep is highly evolved, the stupid animals are less frequently immobilized by deep sleep than the smart ones. But why should they sleep deeply at all? Why should a state of such deep immobilization ever have evolved? Perhaps one useful hint about the original function of sleep is to be found in the fact that dolphins and whales and aquatic mammals in general seem to sleep very little. There is, by and large, no place to hide in the ocean. Could it be that, rather than increasing an animal's vulnerability, the function of sleep is to decrease it? Wilse Webb of the University of Florida and Ray Meddis of London University have suggested this to be the case. It is conceivable that animals who are too stupid to be quiet on their own initiative are, during periods of high risk, immobilized by the implacable arm of sleep. The point seems particularly clear for the young of predatory animals. This is an interesting notion and probably at least partly true.
The ways of history are so intricate and the motivations of human actions so complex that it is always hazardous to attempt to represent events covering a number of years, a multiplicity of persons, and distant localities as the expression of one intellectual or social movement; yet the historical process which culminated in the ascent of Thomas Jefferson to the presidency can be regarded as the outstanding example not only of the birth of a new way of life but of nationalism as a new way of life. The American Revolution represents the link between the seventeenth century, in which modern England became conscious of itself, and the awakening of modern Europe at the end of the eighteenth century. It may seem strange that the march of history should have had to cross the Atlantic Ocean, but only in the North American colonies could a struggle for civic liberty lead also to the foundation of a new nation.
Here, in the popular rising against a "tyrannical" government, the fruits were more than the securing of a freer constitution. They included the growth of a nation born in liberty by the will of the people, not from the roots of common descent, a geographic entity, or the ambitions of king or dynasty. With the American nation, for the first time, a nation was born,
not in the dim past of history but before the eyes of the whole world.
People appear to be born to compute. The numerical skills of children develop so early and so inexorably that it is easy to imagine an internal clock of mathematical maturity guiding their growth. Not long after learning to walk and talk, they can set the table with impressive accuracy-- one knife, one spoon, one fork, for each of the five chairs. Soon they are capable of noting that they have placed five knives, spoons and forks on the table and, a bit later, that this amounts to fifteen pieces of silverware. Having thus mastered addition, they move on to subtraction. It seems almost reasonable to expect that if a child were secluded on a desert island at birth and retrieved seven years later, he or she could enter a second-grade mathematics class without any serious problems of intellectual adjustment.
Of course, the truth is not so simple. This century, the work of cognitive psychologists has illuminated the subtle forms of daily learning on which intellectual progress depends. Children were observed as they slowly grasped -- or, as the case might be, bumped into -- concepts that adults take for granted, as they refused, for instance, to concede that quantity is unchanged as water pours from a short stout glass into a tall thin one.
Psychologists have since demonstrated that young children, asked to count the pencils in a pile, readily report the number of blue or red pencils, but must be coaxed into finding the total. Such studies have suggested that the rudiments of mathematics are mastered gradually, and with effort. They have also suggested that the very concept of abstract numbers - the idea of a oneness, a twoness, a threeness that applies to any class of objects and is a prerequisite for doing anything more mathematically demanding than setting a table - is itself far from innate.
1、some people believe that marriage is an out of date institution. what is your opinion.write a composition of over 200 words to defend your viewpoint.
Yes ,because marriage is still important in society as a rational view of what a loving committed relationship actually is: if love is so transient in society it is important to have a foundation to hold couples together to realise that friendship, support, trust and commitment are more important. We cannot encourage couples to live a more relaxed relationship when as parents they are responsible for a child’s welfare.
2、as a graduate student,what is your idea on graduate education in china?write a composition of over 200 words entitled My View on Graduate Education in China .voice your view with ample evidence.
I'm a graduate student in South China Normal University,major in educational technology.I am a freshman in graduate school and after two mouth's life of being a graduate student ,I found a big difference between undergraduate and postgraduate.You can see undergraduates chat in WeChat using their mobile device in classroom and do not engage attention and interest to what teachers say,or just play computer games in dorm,but you can not see a postgraduate do these things.After all,postgraduate should make something different in three year's graduate life.
After my deliberate thinking,I make a do-list to remind myself to be a qualified graduate student.
1.Read professional books and find a topic attract my interest to be research point ,and study further of it.
2.Read magazine related to my profession,keep a sharp for the latest idea and concept.
3.Read more literature,and do literature review.(This is a sinifcant approach to cultivate professional attainment)
4.Insist on an hour English learning,include read BBC News and use English application.
5.Participate in some activities that can improve my ability.
There still many things should be on my to-do list, I will continuously improve my list and enrich everday.