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Scientists say they have discovered hints of alien life on the Saturn"s moon. The discovery of a sort of life was announced after researchers at the US space agency, NASA, analyzed data from spacecraft Cassini, which pointed to, the existence of methane-based form of life on Saturn"s biggest moon.Scientists have reportedly discovered clues showing primitive alien beings are "breathing" in Titan"s dense atmosphere filled with hydrogen.They argue that hydrogen gets absorbed before hitting Titan"s planet-like surface covered with methane lakes and rivers. This, they say, points to the existence of some "bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth."We suggested hydrogen consumption because it"s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth," says NASA scientist Chris McKay. "If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth."To date, scientists have not yet detected this form of life anywhere, though there are liquid water based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Fahrenheit), a methane based organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan"s surface and much too cold to support life as we know it.Scientists had expected the Sun"s interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan"s surface. But Cassini detected no acetylene on the surface.The absence of detectable acetylene on the Titan"s surface can very well have a non-biological explanation, said Mark Alien, a principal investigator of the NASA Titan team."Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed," Alien said, "We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process, without biology, can explain these results." What is "Cassini" in Paragragh 5
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Trees should only be pruned when there is a good and clear reason for doing so and, fortunately, the number of such reasons is small. Pruning involves the cutting away of overgrown and unwanted branches, and the inexperienced gardener can be encouraged by the thought that more damage results from doing it unnecessarily than from leaving the tree to grow in its own way.First, pruning may be done to make sure that trees have a desired shape or size. The object may be to get a tree of the right height, and at the same time to help the growth of small side branches which will thicken its appearance or give it a special shape. Secondly, pruning may be done to make the tree healthier. You may cut diseased or dead wood, or branches that are rubbing against each other and thus cause wounds. The health of a tree may be encouraged by removing branches that are blocking up the centre and so preventing the free movement of air.One result of pruning is that an open wound is left on the tree and this provides an easy entry for disease, but it is a wound that will heal. Often there is a race between the healing and the disease as to whether the tree will live or die, so that there is a period when the tree is at risk. It should be the aim of every gardener to reduce which has been pruned smooth and clean, for healing will be slowed down by roughness. You should allow the cut surface to dry for a few hours and then paint it with one of the substances available from garden shops produced especially for this purpose. Pruning is usually without interference from the leaves and also it is very unlikely that the cuts you make will bleed. If this does happen, it is, of course, impossible to paint them properly. Trees become unhealthy if the gardener ______.
Deception and delusions are esteemed for soundest truths, while reality is fabulous. If men would steadily observe realities only, and not allow themselves to be cheated, life, to compare it with such things as we know, would be like a fairy tale and the Arabian Nights" Entertainments.If we respect only what is inevitable and has a right to be, music and poetry would resound along the streets. When we are unhurried and wise, we perceive that only great and worthy things have any permanent and absolute existence, and that petty fears and petty pleasure are but the shadow of reality. This is always exciting and great.By closing the eyes and falling asleep, by allowing to be deceived by shows, men establish and confirm their daily life of routine and habit everywhere, which still is built on purely false foundation. Children, who play life, differentiate its true law and relations more clearly than men, who fail to live worthily, but who think that they are wiser by experience, that is, by failure. If a man should give us an account of the realities he saw, we should not recognize the place in his description. Look at a meeting-house, or a court-house, or a jail, or a shop. Or a dwelling-house and say what that thing really is before a true gaze, and they would all go to pieces in your account of them. Men esteem truth remote, in the outskirts of the system, behind the farthest star, before Adam and after the last man. In eternity there is indeed something true and great. But all these times and places and occasions are now and here. God himself culminates in the present moment, and will never be more divine in the lapse of all ages. And we are enabled to understand at all what is great and noble only by the continuing understanding and immersing of the reality that surrounds us.The universe constantly and obediently answers to our conceptions; whether we travel fast or slow, the track is laid for us. Let us spend our lives in conceiving then. The poet or the artist never yet had as fair and noble a design but some of his posterity at least could accomplish it. According to the passage, the art is ______.
审计人员形成审计结论、发表审计意见的直接依据是指______
Why the inductive and mathematical sciences, after their first rapid development at the culmination of Greek civilization, advanced so slowly for two thousand years—and why in the following two hundred years a knowledge of natural and mathematical science has accumulated, which so vastly exceeds all that was previously known that these sciences may be justly regarded as the products of our own times—are questions which have interested the modern philosopher not less than the objects with which these sciences are more immediately familiar.The explanation which has become commonplace, that the ancients employed deduction chiefly in their scientific inquiries, while the modems employ induction, proves to be too narrow. For all knowledge is founded on observation, and proceeds from this by analysis, by induction and deduction, and if possible by verification, or by steps which are indeed parts of one method.A failure to employ adequately any one of these partial methods, an imperfection in the arts and resources of observation and experiment, carelessness in observation, neglect of relevant facts—these are the faults which cause all failures to ascertain truth; but this statement does not explain why the modem is possessed of a greater virtue, and by what means he attained his superiority. Much less does it explain the sudden growth of science in recent time.The attempt to discover the explanation of this phenomenon in theantithesis(对立面；对照；对仗) of "facts" and "theories"—in the neglect among the ancients of the former, and their too exclusive attention to the latter—proves also to be too narrow, as well as open to the charge of vagueness. Theories, if true, are facts—a particular class of facts indeed, generally complex, and if a logical connection subsists between their constituents, have all the positive attributes of theories.Nevertheless, this distinction, however inadequate it may be to explain the source of true method in science, is well founded, and suggests an important character in true method. A theory, on the other hand, if true has all the characteristics of a fact, except that its verification is possible only by indirect, remote, and difficult means. To convert theories into facts is to add simple verification, and the theory thus acquires the full characteristics of a fact. All the following statements can be reasons for the failure of explanation for questions mentioned in Paragraph 1 except for ______.
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