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[passage-header]Read the passage given below and answer the question that follows:[/passage-header]Frazier and Mosteller assert that medical research could be improved by a move toward larger, simpler clinical trials of medical treatments. Currently, researchers collect far more background information on patients than is strictly required for their trials - substantially more than hospitals collect -thereby escalating costs of data collection, storage, and analysis. Although limiting information collection could increase the risk that researchers will overlook facts relevant to a study, Frazier and Mosteller contend that such risk, never entirely eliminable from research, would still be small in most studies. Only in research on entirely new treatments are new and unexpected variables likely to arise.
Frazier and Mosteller propose not only that researchers limit data collection on individual patients but also that researchers enroll more patients in clinical trials, 45635thereby obtaining a more representative sample of the total population with the disease under study. Often researchers restrict study participation to patients who have no ailments besides those being studied65629. A treatment judged successful under these ideal conditions can then be evaluated under normal conditions. Broadening the range of trial participants, 99220Frazier and Mosteller suggest, would enable researchers to evaluate a treatment's efficacy for diverse patients under various conditions and to evaluate its effectiveness for different patient subgroups54827. For example, the value of a treatment for a progressive disease may vary according to a patient's stage of disease. Patients' ages may also affect a treatment's efficacy.

While the most abundant and dominant species within a particular ecosystem is often crucial in perpetuating the ecosystem, a "keystone" species, here defined as one whose effects are much larger than would be predicted from its abundance, can also play a vital role. But because complex species interactions may be involved, identifying a keystone species by removing the species and observing changes in the ecosystem is problematic. It might seem that certain traits would clearly define a species as a keystone species; for example, Pisaster ochraceus is often a keystone predator because it consumes and suppresses mussel populations, which in the absence of this starfish can be a dominant species. But such predation on a dominant or potentially dominant species occurs in systems that do as well as in systems that do not have species that play keystone roles. Moreover, whereas P. ochraceous occupies an unambiguous keystone role on wave-exposed rocky headlands, in more wave-sheltered habitats the impact of P. ochraceus predation is weak or non-existent, and at certain sites, sand burial is responsible for eliminating mussels. 99342Keystone status appears to depend on context, whether of particular geography or of such factors as community diversity (for example, a reduction in species diversity may thrust more of the remaining species into keystone roles) and length of species interaction (since newly arrived species, in particular, may dramatically affect ecosystems)42146.

[passage-header]Read the passage given below and answer the question that follows:[/passage-header]There are recent reports of apparently drastic declines in amphibian populations and of extinctions of a number of the world's endangered amphibian species. 28634These declines, if real, may be signs of a general trend toward extinction, and many environmentalists have claimed that immediate environmental action is necessary to remedy this "94875amphibian crisis," which, in their view, is an indicator of general and catastrophic environmental degradation due to human activity.

To evaluate these claims, it is useful to make a preliminary distinction that is far too often ignored. A declining population should not be confused with an endangered one. An endangered population is always rare, almost always small, and, by definition, under constant threat of extinction even without a   proximate cause in human activities. Its disappearance, however unfortunate, should come as no great surprise. Moreover, chance events - which may indicate nothing about the direction of trends in population size - may lead to its extinction. The probability of extinction due to such random factors depends on the population size and is independent of the prevailing direction of change in that size.

For biologists, population declines are potentially more worrisome than extinctions. Persistent declines, especially in large populations, indicate a changed ecological context. Even here, distinctions must again be made among declines that are only apparent (in the sense that they are part of habitual cycles or of normal fluctuations), declines that take a population to some lower but still acceptable level and those that threaten extinction (e.g by taking the number of individuals below the minimum viable population). Anecdotal reports of population decreases cannot distinguish among these possibilities, and some amphibian populations have shown strong fluctuations in the past. 

It is indisputably true that there is simply not enough long-term scientific data on amphibian populations to enable researchers to identify real declines in amphibian populations. Many fairly common amphibian species declared all but extinct after several declines in the 1950s and 1960s have subsequently recovered, and so might the apparently declining populations that have generated the current appearance of an amphibian crisis. Unfortunately, long-term data will not soon be forthcoming and postponing environmental action while we wait for it may doom species and whole ecosystems to extinction.

While the most abundant and dominant species within a particular ecosystem is often crucial in perpetuating the ecosystem, a "keystone" species, here defined as one whose effects are much larger than would be predicted from its abundance, can also play a vital role. But because complex species interactions may be involved, identifying a keystone species by removing the species and observing changes in the ecosystem is problematic. It might seem that certain traits would clearly define a species as a keystone species; for example, Pisaster ochraceus is often a keystone predator because it consumes and suppresses mussel populations, which in the absence of this starfish can be a dominant species. But such predation on a dominant or potentially dominant species occurs in systems that do as well as in systems that do not have species that play keystone roles. Moreover, whereas P. ochraceous occupies an unambiguous keystone role on wave-exposed rocky headlands, in more wave-sheltered habitats the impact of P. ochraceus predation is weak or non-existent, and at certain sites, sand burial is responsible for eliminating mussels. 99342Keystone status appears to depend on context, whether of particular geography or of such factors as community diversity (for example, a reduction in species diversity may thrust more of the remaining species into keystone roles) and length of species interaction (since newly arrived species, in particular, may dramatically affect ecosystems)42146.

[passage-header]Read the passage given below and answer the question that follows:[/passage-header]Frazier and Mosteller assert that medical research could be improved by a move toward larger, simpler clinical trials of medical treatments. Currently, researchers collect far more background information on patients than is strictly required for their trials - substantially more than hospitals collect -thereby escalating costs of data collection, storage, and analysis. Although limiting information collection could increase the risk that researchers will overlook facts relevant to a study, Frazier and Mosteller contend that such risk, never entirely eliminable from research, would still be small in most studies. Only in research on entirely new treatments are new and unexpected variables likely to arise.
Frazier and Mosteller propose not only that researchers limit data collection on individual patients but also that researchers enroll more patients in clinical trials, 45635thereby obtaining a more representative sample of the total population with the disease under study. Often researchers restrict study participation to patients who have no ailments besides those being studied65629. A treatment judged successful under these ideal conditions can then be evaluated under normal conditions. Broadening the range of trial participants, 99220Frazier and Mosteller suggest, would enable researchers to evaluate a treatment's efficacy for diverse patients under various conditions and to evaluate its effectiveness for different patient subgroups54827. For example, the value of a treatment for a progressive disease may vary according to a patient's stage of disease. Patients' ages may also affect a treatment's efficacy.

[passage-header]Read the passage and answer the question that follows:[/passage-header]After evidence was obtained in the 1920s that the universe is expanding, it became reasonable to ask: Will the universe continue to expand indefinitely, or is there enough mass in it for the mutual attraction of its constituents to bring this expansion to a halt? It can be calculated that the critical density of matter needed to brake the expansion and "close" the universe is equivalent to three hydrogen atoms per cubic meter. But the density of the observable universe-luminous matter in the form of galaxies-comes to only a fraction of this. If the expansion of the universe is to stop, there must be enough invisible matter in the universe to exceed the luminous matter in density by a factor of roughly 70.

Our contribution to the search for this "missing matter" has been to study the rotational velocity of galaxies at various distances from their center of rotation. It has been known for some time that outside the bright nucleus of a typical spiral galaxy luminosity falls off rapidly with distance from the center. If luminosity were a true indicator of mass, most of the mass would be concentrated toward the center. Outside the nucleus, the rotational velocity would decrease geometrically with distance from the center, in conformity with Kepler's law. Instead, we have found that the rotational velocity in spiral galaxies either remains constant with increasing distance from the center or increases slightly. This unexpected result indicates that the fall off in luminous mass with distance from the center is balanced by an increase in nonluminous mass.

Our findings suggest that as much as 90 percent of the mass of the universe is not radiating at any wavelength with enough intensity to be detected on the Earth. Such dark matter could be in the form of extremely dim stars of low mass, of large planets like Jupiter, or of black holes, either small or massive. While it has not yet been determined whether this mass is sufficient to close the universe, some physicists consider it significant that estimates are converging on the critical value.

[passage-header]Read the passage given below and answer the question that follows:[/passage-header]   77941While they had been young, no event in the social world of Elsinore had been a success without the lovely De Coninck sisters. They were the heart and soul of all the gayety of the town. When they entered its ballrooms, the ceilings of sedate old merchants' houses seemed to lift a little, and the walls to spring out in luminous Ionian columns, bound with a vine. 84433When one of them opened the ball, light as a bird, bold as a thought, she consecrated the gathering to the gods of true joy of life, from whose presence care and envy are banished23578. They could sing duets like a pair of nightingales in a tree, and imitate without effort and without the slightest malice the voices of all the beau monde of Elsinore, so as to make the paunches of their father's friends, the matadors of the town, shake with laughter around their card tables. They could make up a charade or a game of forfeits in no time, and when they had been out for their music lessons, or to the Promenade, they came back brimful of tales of what had happened, or of tales out of their own imaginations, one whim stumbling over the other94702.
   And then, within their own rooms, they would walk up and down the floor and weep, or sit in the window and look out over the harbor and wring their hands in their laps, or lie in bed at night and cry bitterly, for no reason in the world. They would talk, then, of life with the black bitterness of two Timons of Athens, and give Madam back an 24931uncanny feeling, as in an atmosphere of corrodent rust. Their mother, who did not have the curse50091 in her blood, would have been badly frightened had she been present at these moments, and would have suspected some unhappy love affair. Their father would have understood them, and have grieved on their behalf, but he was occupied with his affairs and did not come into his daughters' rooms. Only this elderly female servant, whose temperament was as different as possible from theirs, would understand them in her way, and would keep it all within her heart, as they did themselves, with mingled despair and pride. Sometime she would try to comfort them. When they cried out, "Hanne, is it not terrible that there is so much lying, so much falsehood, in the world?" she said, "Well, what of it? It would be worse still if it were actually true, all that they tell."
   Then again the girls would get up, dry their tears, try on their new bonnets before the glass, plan their theatricals and sleighing parties, shock and gladden the hearts of their friends, and have the whole thing over again. They seemed as unable to keep from one extremity as from the other. In short, they were born melancholiac, such as make others happy and are themselves helplessly unhappy, creatures of playfulness, charm, and salt tears, of fine fun and everlasting loneliness.                [passage-footer]
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[passage-header]"To my Honoured Kinsman John Driden, of
Chesterton, in the County of Huntingdon, Esq."[/passage-header] 51162How blessed is he, who leads a country life,
Unvexed with anxious cares, and 83919void of strife!
Who, studying peace, and shunning civil rage,
Enjoyed his youth, and now enjoys his age:
All who deserve his love, he makes his own;

58882And, to be loved himself, needs only to be known.
26757Just good and wise, contending neighbours come,
From your award to wait 35083their final doom;
84568And, foes before, return in friendship home
Without their cost, you terminate the cause,

72006And save the expense of long litigious laws;
58159Where suits are traversed, and so little won,
28845That he who conquers is but last undone;
Such are not your decrees; but so designed,
The sanction leaves a lasting peace behind;

Like your own soul, serene, a pattern of your mind.
Promoting concord, and composing strife,
Lord of yourself, encumbered with a wife;
Where, for a year, a month, perhaps a night,
88266Long penitence succeeds a short delight;
30941Minds are so badly matched, that even the first,
35359Though paired by heaven, in Paradise were cursed.
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[passage-header]Read the passage and answer the question that follows:[/passage-header]   Eugene Coristine and Farquhar Wilkinson were youngish bachelors and fellow members of the Victoria and Albert Literary Society. 77465Thither, on Wednesday evenings, when respectable church members are 40212wending their way to weekly service, they hastened regularly, to meet with a band of like-minded young men, and spend a literary hour or two74574. In various degrees of fluency, they debated the questions of the day; they read essays with a wide range of style and topic; they gave readings from popular authors, and contributed airy creations in prose and in verse to the Society's manuscript magazine. Wilkinson, the older and more sedate of the two, who wore a tightly-buttoned blue frock coat and an eyeglass, was a schoolmaster, pretty 48366well up in the Toronto Public Schools. Coristine was a lawyer in full practice, but his name did not appear on the card of the firm which profited by his services. He was taller than his friend, more jauntily dressed, and was of a more 73151mercurial temperament than the schoolmaster, for whom, however, he entertained a profound respect. Different as they were, they were linked together by an ardent love of literature, especially poetry, by scientific pursuits, Coristine as a botanist, and Wilkinson as a dabbler in geology, and by a firm determination to resist, or rather to shun, the allurements of female society. Many lady teachers wielded the pointer in rooms not far removed from those in which Mr. Wilkinson held sway, but he did not condescend to be on terms even of bowing acquaintance with any one of them. There were several young lady typewriters of respectable city connections in the offices of Messrs. Tyler. Woodruff and White, but the young Irish lawyer passed them by without a glance. These bachelors were of the opinion that women were bringing the dignity of law and education to the dogs.
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[passage-header]Read the passage given below and answer the question that follows. [/passage-header]    There comes to the house of Yen Chow a Chinese merchant of wealth and influence. His eyes dwell often upon Ah Leen. He whispers to her father. Yen Chow puffs his pipe and muses, assuredly a 50231great slight has been put upon his family. A divorce would show proper pride. It was not the Chinese way, but was not the old order passing away and the new order taking its place? Aye, even in China, the old country that had seemed as if it would ever remain old. He speaks to Ah Leen.
   "Nay, father, nay," she returns. "Thou hast the power to send my love away from me, but thou canst not compel me to hold out my arms to another."
   "But," protests her mother, "thy lover hath forgotten thee. Another hath borne him a child."
    A flame rushes over Ah Leen's face; then she 42349becomes white as a water lily. She plucks a leaf of scented geranium, crushes it between her fingers and casts it away. The 21728perfume clings to the hands, she lays on her mother's bosom.
   "Thus," says she, "the fragrance of my crushed love will ever cling to Ming Hoan."
    It is evening. The electric lights are shining through the vines. Out of the gloom beyond their radius comes a man. The American girl, seated in a quiet corner of the veranda, sees his face. It is eager and the eyes are full of love and fate. Then she sees Ah Leen. Tired of women's gossip, the girl has come to gaze upon the moon, hanging in the sky above her like a pale yellow pearl.
   There is a cry from the approaching man. It is echoed by the girl. In a moment she is leaning upon his breast.
   "Ah!" she cries, raising her head and looking into his eyes. "I knew that though another had bound you by human ties, to me you were linked by my love divine."
   "Another! Human ties!" exclaims the young man. He exclaims without explaining---for the sins of parents must not be uncovered---why there has been silence between them for so long. Then he lifts her face to his and gently reproaches her. "Ah Leen, you have dwelt only upon your love for me. Did I not bid thee, 'Forget not to remember that I love thee!'"
   The American girl steals away. The happy Ming Hoan is unaware that as she flits lightly by him and his bride she is repeating to herself his words, and hoping that it is not too late to send to someone a message of recall.
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