The fossil remains of the first flying vertebrates, the pterosaurs, have intrigued paleontologists for more than two centuries. How such large creatures, which weighed in some cases as much as a piloted hang-glider and had wingspans from 8 to 12 meters, solved the problems of powered flight, and exactly what these creatures were—reptiles or birds—are among the questions scientists have puzzled over.
Perhaps the least controversial assertion about the pterosaurs is that they were reptiles. Their skulls, pelvises, and hind feet are reptilian. The anatomy of their wings suggests that they did not evolve into the class of birds. In pterosaurs a greatly elongated fourth finger of each forelimb supported a wing-like membrane. The other fingers were short and reptilian, with sharp claws. In birds the second finger is the principal strut of the wing, which consists primarily of feathers. If the pterosaurs walked on all fours, the three short fingers may have been employed for grasping. When a pterosaur walked or remained stationary, the fourth finger, and with it the wing, could only turn upward in an extended inverted V-shape along each side of the animal’s body.
The pterosaurs resembled both birds and bats in their overall structure and proportions. This is not surprising because the design of any flying vertebrate is subject to aerodynamic constraints. Both the pterosaurs and the birds have hollow bones, a feature that represents a savings in weight. In the birds, however, these bones are reinforced more massively by internal struts.
Although scales typically cover reptiles, the pterosaurs probably had hairy coats. T. H. Huxley reasoned that flying vertebrates must have been warm-blooded because flying implies a high rate of metabolism, which in turn implies a high internal temperature. Huxley speculated that a coat of hair would insulate against loss of body heat and might streamline the body to reduce drag in flight. The recent discovery of a pterosaur specimen covered in long, dense, and relatively thick hairlike fossil material was the first clear evidence that his reasoning was correct.
Efforts to explain how the pterosaurs became airborne have led to suggestions that they launched themselves by jumping from cliffs, by dropping from trees, or even by rising into light winds from the crests of waves. Each hypothesis has its difficulties. The first wrongly assumes that the pterosaurs’ hind feet resembled a bat’s and could serve as hooks by which the animal could hang in preparation for flight. The second hypothesis seems unlikely because large pterosaurs could not have landed in trees without damaging their wings. The third calls for high waves to channel updrafts. The wind that made such waves however, might have been too strong for the pterosaurs to control their flight once airborne.
It can be inferred from the passage that scientists now generally agree that the (A) enormous wingspan of the pterosaurs enabled them to fly great distances
(B) structure of the skeleton of the pterosaurs suggests a close evolutionary relationship to bats (C) fossil remains of the pterosaurs reveal how they solved the problem of powered flight (D) pterosaurs were reptiles
(E) pterosaurs walked on all fours
2. The author views the idea that the pterosaurs became airborne by rising into light winds created by waves as (A) revolutionary (B) unlikely (C) unassailable (D) probable
(E) outdated
3. According to the passage, the skeleton of a pterosaur can be distinguished from that of a bird by the
(A) size of its wingspan
(B) presence of hollow spaces in its bones (C) anatomic origin of its wing strut
(D) presence of hooklike projections on its hind feet
(E) location of the shoulder joint joining the wing to its body
4. The ideas attributed to T. H. Huxley in the passage suggest that he would most likely agree with which of the following statements?
(A) An animal’s brain size has little bearing on its ability to master complex behaviors.
(B) An animal’s appearance is often influenced by environmental requirements and physical capabilities.
(C) Animals within a given family group are unlikely to change their appearance dramatically over a period of time.
(D) The origin of flight in vertebrates was an accidental development rather than the outcome of specialization or adaptation.
(E) The pterosaurs should be classified as birds, not reptiles.
Which of the following best describes the organization of the last paragraph of the passage? (A) New evidence is introduced to support a traditional point of view.
(B) Three explanations for a phenomenon are presented, and each is disputed by means of specific information.
(C) Three hypotheses are outlined, and evidence supporting each is given.
(D) Recent discoveries are described, and their implications for future study are projected. LSAT第27套 SECTION I
Most office workers assume that the messages they send to each other via electronic mail are as private as a telephone call or a face-to-face meeting. That assumption is wrong. Although it is illegal in many areas for an employer to eavesdrop on private conversations or telephone calls—even if they take place on a company-owned telephone—there are no clear rules governing electronic mail. In fact, the question of how private electronic mail transmissions should be has emerged as one of the more complicated legal issues of the electronic age.
People’s opinions about the degree of privacy that electronic mail should have vary depending on whose electronic mail system is being used and who is reading the messages. Does a government office, for example, have the right to destroy electronic messages created in the course of running the government, thereby denying public access to such documents? Some hold that government offices should issue guidelines that allow their staff to delete such electronic records, and defend this practice by claiming that the messages thus deleted already exist in paper versions whose destruction is forbidden. Opponents of such practices argue that the paper versions often omit such information as who received the messages and when they received them, information commonly carried on electronic mail systems. Government officials, opponents maintain, are civil servants; the public should thus have the right to review any documents created during the conducting of government business.
Questions about electronic mail privacy have also arisen in the private sector. Recently, two employees of an automotive company were discovered to have been communicating disparaging
information about their supervisor via electronic mail. The supervisor, who had been monitoring the communication, threatened to fire the employees. When the employees filed a grievance complaining that their privacy had been violated, they were let go. Later, their court case for unlawful termination was dismissed; the company’s lawyers successfully argued that because the company owned the computer system, its supervisors had the right to read anything created on it.
In some areas, laws prohibit outside interception of electronic mail by a third party without proper authorization such as a search warrant. However, these laws do not cover “inside” interception such as occurred at the automotive company. In the past, courts have ruled that interoffice communications may be considered private only if employees have a “reasonable expectation” of privacy when they send the messages. The fact is that no absolute guarantee of privacy exists in any computer system. The only solution may be for users to scramble their own messages with encryption codes; unfortunately, such complex codes are likely to undermine the principal virtue of electronic mail: its convenience.
1. Which one of the following statements most accurately summarizes the main point of the passage?
(A) Until the legal questions surrounding the privacy of electronic mail in both the public and private sectors have been resolved, office workers will need to scramble their electronic mail messages with encryption codes.
(B) The legal questions surrounding the privacy of electronic mail in the work place can best be resolved by treating such communications as if they were as private as telephone conversations or face-to-face meetings.
(C) Any attempt to resolve the legal questions surrounding the privacy of electronic mail in the workplace must take into account the essential difference between public-sector and private sector business.
(D) At present, in both the public and private sectors, there seem to be no clear general answers to the legal questions surrounding the privacy of electronic mail in the workplace.
(E) The legal questions surrounding the privacy of electronic mail in the workplace of electronic mail in the workplace can best be resolved by allowing supervisors in public-sector but not private-sector offices to monitor their employees’ communications.
2. According to the passage, which one of the following best expresses the reason some people use to oppose the deletion of electronic mail records at government offices?
(A) Such deletion reveals the extent of government’s unhealthy obsession with secrecy.
(B) Such deletion runs counter to the notion of government’s accountability to its constituency. (C) Such deletion clearly violates the legal requirement that government offices keep duplicate copies of all their transactions.
(D) Such deletion violates the government’s own guidelines against destruction of electronic records.
(E) Such deletion harms relations between government employees and their supervisors. 3. Which one of the following most accurately states the organization of the passage?
(A) A problem is introduced, followed by specific examples illustrating the problem: a possible solution is suggested, followed by an acknowledgment of its shortcomings.
(B) A problem is introduced, followed by explications of two possible solutions to the problem: the first solution is preferred to the second, and reasons are given for why it is the better
alternative.
(C) A problem is introduced, followed by analysis of the historical circumstances that helped bring the problem about a possible solution is offered and rejected as being only a partial remedy.
(D) A problem is introduced, followed by enumeration of various questions that need to be answered before a solution can be found: one possible solution is proposed and argued for.
(E) A problem is introduced, followed by descriptions of two contrasting approaches to thinking about the problem: the second approach is preferred to the first, and reasons are given for why it is more likely to yield a successful solution.
4. Based on the passage, the author’s attitude towards interception of electronic mail can most accurately be described as:
(A) outright disapproval of the practice (B) support for employers who engage in it
(C) support for employees who lose their jobs because of it (D) intellectual interest in its legal issues
(E) cynicism about the motives behind the practice
5. It can be inferred from the passage that the author would most likely hold which one of the following opinions about an encryption system that could encodes and decode electronic mail messages with a single keystroke?
(A) It would be an unreasonable burden on a company’s ability to monitor electronic mail created by its employees.
(B) It would significantly reduce the difficulty of attempting to safeguard the privacy of electronic mail.
(C) It would create substantial legal complications for companies trying to prevent employees from revealing trade secrets to competitors.
(D) It would guarantee only a minimal level of employee privacy, and so would not be worth the cost involved in installing such a system.
(E) It would require a change in the legal definition of “reasonable expectation of privacy” as it applies to employer-employee relations.
SECTION B
Some recent historians have argued that life in the British colonies in America from approximately 1763 to 1789 was marked by internal conflicts among colonists. Inheritors of some of the viewpoints of early twentieth-century Progressive historians such as Beard and Becker, these recent historians have put forward arguments that deserve evaluation.
The kind of conflict most emphasized by these historians is class conflict. Yet with the Revolutionary War dominating these years, how does one distinguish class conflict within that larger conflict? Certainly not by the side a person supported. Although many of these historians have accepted the earlier assumption that Loyalists represented an upper class, new evidence indicates that Loyalists, like rebels, were drawn from all socioeconomic classes. (It is nonetheless probably true that a larger percentage of the well-to-do joined the Loyalists than joined the rebels.) Looking at the rebel side, we find little evidence for the contention that lower-class rebels were in conflict with upper-class rebels. Indeed, the war effort against Britain tended to suppress class conflicts. Where it did not, the disputing rebels of one or another class usually became Loyalists. Loyalism thus operated as a safety valve to remove socioeconomic discontent
that existed among the rebels. Disputes occurred, of course, among those who remained on the rebel side, but the extraordinary social mobility of eighteenth-century American society (with the obvious exception of slaves) usually prevented such disputes from hardening along class lines. Social structure was in fact so fluid—though recent statistics suggest a narrowing of economic opportunity as the latter half of the century progressed—that to talk about social classes at all requires the use of loose economic categories such as rich, poor, and middle class, or eighteenth-century designations like “the better sort.” Despite these vague categories, one should not claim unequivocally that hostility between recognizable classes cannot be legitimately observed. Outside of New York, however, there were very few instances of openly expressed class antagonism.
Having said this, however, one must add that there is much evidence to support the further claim of recent historians that sectional conflicts were common between 1763 and 1789. The “Paxton Boys” incident and the Regulator movement are representative examples of the widespread, and justified, discontent of western settlers against colonial or state governments dominated by eastern interests. Although undertones of class conflict existed beneath such hostility, the opposition was primarily geographical. Sectional conflict—which also existed between North and South—deserves further investigation.
In summary, historians must be careful about the kind of conflict they emphasize in eighteenth-century America. Yet those who stress the achievement of a general consensus among the colonists cannot fully understand that consensus without understanding the conflicts that had to be overcome or repressed in order to reach it.
17. The author considers the contentions made by the recent historians discussed in the passage to be
(A) potentially verifiable (B) partially justified
(C) logically contradictory (D) ingenious but flawed
(E) capricious and unsupported
19. According to the passage, Loyalism during the American Revolutionary War served
the function of
(A) eliminating the disputes that existed among those colonists who supported the
rebel cause (B) drawing upper, as opposed to lower, socioeconomic classes away from the rebel
cause (C) tolerating the kinds of socioeconomic discontent that were not allowed to exist
on the rebel side (D) channeling conflict that existed within a socioeconomic class into the war effort
against the rebel cause (E) absorbing members of socioeconomic groups on the rebel side who felt
themselves in contention with members of other socioeconomic groups
The passage suggests that the author would be likely to agree with which of the following statements about the social structure of eighteenth-century American society? I. It allowed greater economic opportunity than it did social mobility.
II. It permitted greater economic opportunity prior to 1750 than after 1750. III. It did not contain rigidly defined socioeconomic divisions.
IV. It prevented economic disputes from arising among members of the society. (A) I and IV only (B) II and III only (C) III and IV only (D) I, II, and III only (E) I, II, III, and IV
21. It can be inferred from the passage that the author would be most likely to agree with which of the following statements regarding socioeconomic class and support for the rebel and Loyalist causes during the American Revolutionary War? (A) Identifying a person’s socioeconomic class is the least accurate method of ascertaining which side that person supported.
(B) Identifying a person as a member of the rebel or of the Loyalist side does not necessarily reveal that person’s particular socioeconomic class.
(C) Both the rebel and the Loyalist sides contained members of all socioeconomic classes, although there were fewer disputes among socioeconomic classes on the Loyalist side.
(D) Both the rebel and the Loyalist sides contained members of all socioeconomic classes, although the Loyalist side was made up primarily of members of the upper classes.
According to the passage, which of the following is a true statement about sectional conflicts in America between 1763 and 1789?
(A) These conflicts were instigated by eastern interests against western settlers. (B) These conflicts were the most serious kind of conflict in America. (C) The conflicts eventually led to openly expressed class antagonism. (D) These conflicts contained an element of class hostility. (E) These conflicts were motivated by class conflicts.
The recent, apparently successful, prediction by mathematical models of an appearance of El Nino—the warm ocean current that periodically develops along the Pacific coast of South America—has excited researchers. Jacob Bjerknes pointed out over 20 years ago how winds might create either abnormally warm or abnormally cold water in the eastern equatorial Pacific. Nonetheless, until the development of the models no one could explain why conditions should regularly shift from one to the other, as happens in the periodic oscillations between appearances of the warm El Nino and the cold so-called anti-El Nino. The answer, at least if the current model that links the behavior of the ocean to that of the atmosphere is correct, is to be found in the ocean.
It has long been known that during an El Nino, two conditions exist: (1) unusually warm water extends along the eastern Pacific, principally along the coasts of Ecuador and Peru, and (2) winds blow from the west into the warmer air rising over the warm water in the east. These winds tend to create a feedback mechanism by driving the warmer surface water into a “pile” that blocks the normal upwelling of deeper, cold water in the east and further warms the eastern water, thus
strengthening the wind still more. The contribution of the model is to show that the winds of an El Nino, which raise sea level in the east, simultaneously send a signal to the west lowering sea level. According to the model, that signal is generated as a negative Rossby wave, a wave of depressed, or negative, sea level, that moves westward parallel to the equator at 25 to 85 kilometers per day. Taking months to traverse the Pacific, Rossby waves march to the western boundary of the Pacific basin, which is modeled as a smooth wall but in reality consists of quite irregular island chains, such as the Philippines and Indonesia.
When the waves meet the western boundary, they are reflected, and the model predicts that Rossby waves will be broken into numerous coastal Kelvin waves carrying the same negative sea-level signal. These eventually shoot toward the equator, and then head eastward along the equator propelled by the rotation of the Earth at a speed of about 250 kilometers per day. When enough Kelvin waves of sufficient amplitude arrive from the western Pacific, their negative sea-level signal overcomes the feedback mechanism tending to raise the sea level, and they begin to drive the system into the opposite cold mode. This produces a gradual shift in winds, one that will eventually send positive sea-level Rossby waves westward, waves that will eventually return as cold cycle-ending positive Kelvin waves, beginning another warming cycle. 21. The primary function of the passage as a whole is to (A) introduce a new explanation of a physical phenomenon
(B) explain the difference between two related physical phenomena
(C) illustrate the limitations of applying mathematics to complicated physical phenomena (D) indicate the direction that research into a particular physical phenomenon should take
(E) clarify the differences between an old explanation of a physical phenomenon and a new model of it
22. Which of the following best describes the organization of the first paragraph? (A) A theory is presented and criticized. (B) A model is described and evaluated.
(C) A result is reported and its importance explained. (D) A phenomenon is noted and its significance debated.
(E) A hypothesis is introduced and contrary evidence presented.
24. According to the model presented in the passage, which of the following normally signals the disappearance of an El Nino?
(A) The arrival in the eastern Pacific of negative sea-level Kelvin waves.
(B) A shift in the direction of the winds produced by the start of an anti-El Nino elsewhere in the Pacific.
(C) The reflection of Kelvin waves after they reach the eastern boundary of the Pacific, along Ecuador and Peru.
(D) An increase in the speed at which negative Rossby waves cross the Pacific.
(E) The creation of a reservoir of colder, deep ocean water trapped under the pile of warmer, surface ocean water.
25. It can be inferred from the passage that which of the following would result fairly immediately from the cessation of the winds of an El Nino?
I. Negative Rossby waves would cease to be generated in the eastern Pacific. II. The sea level in the eastern Pacific would fall.
III. The surface water in the eastern Pacific would again be cooled by being mixed with deep
water. (A) I only (B) II only
(C) I and II only (D) I and III only (E) I, II, and III
26. Which of the following, if true, would most seriously undermine the validity of the model of El Nino that is presented in the passage?
(A) During some years El Nino extends significantly farther along the coasts of Ecuador and Peru than during other years.
(B) During periods of unusually cool temperatures along the eastern Pacific, an El Nino is much colder than normal.
(C) The normal upwelling of cold water in the eastern Pacific depends much more on the local characteristics of the ocean than on atmospheric conditions.
(D) The variations in the time it takes Rossby waves to cross the Pacific depend on the power of the winds that the waves encounter.
(E) The western boundary of the Pacific basin is so irregular that it impedes most coastal Kelvin waves from heading eastward.
汉译英：
1有些人认为多次短时间充电，会对电池造成伤害。事实上，我们大错特错。 2 3
英译汉
作文：the real meaning of weapon control
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