Classical physics defines the vacuum as a state of absence: a vacuum is said to exist in a - 试题答案网问答

第1题

To produce the upheaval in the United States that changed and modernized the domain of hig

her education from the mid-1860s to the mid-1880s, three primary causes interacted. The emergence of a half dozen leaders in education provided the personal force that was needed.

Moreover, an outcry for a fresher, more practical, and more advanced kind of instruction arose among the alumni and friends of nearly all of the old colleges and grew into a movement that overrode all conservative opposition. The aggressive "Young Yale" movement appeared, demanding partial alumni control, a more liberal spirit, and a broader course of study. The graduates of Harvard College simultaneously rallied to relieve the college's poverty and demand new enterprise. Education was pushing toward higher standards in the East by throwing off church leadership everywhere, and in the West by finding a wider range of studies and a new sense of public duty.

The old-style. classical education received its most crushing blow in the citadel of Harvard College, where Dr. Charles Eliot, a young captain of thirty-five, son of a former treasure of Harvard, led the progressive forces. Five revolutionary advances were made during the first years of Dr. Eliot's administration. They were the elevation and amplification of entrance requirements, the enlargement of the curriculum and the development of the elective system, the recognition of graduate study in the liberal arts, the raising of professional training in law, medicine, and the fostering of greater maturity in student life. Standards of admission were sharply advanced in 1872 - 1873 and 1876 ~ 1877. By the appointment of a dean to take charge of student affairs, and a wise handling of discipline, the undergraduates were led to regard themselves more as young gentlemen and less as young animals. One new course of study after another was opened up: science, music, the history of the fine arts, advanced Spanish, political economy, physics, classical philology, and international law.

Which of the following is the author's main purpose in writing the passage？

A．To present the history of Harvard College and compare it with that of Yale University.

B．To criticize the conditions of the U. S. universities in the 19th century.

C．To describe innovations in the U. S. higher education in the late 180Os.

D．To introduce what was happening in major U. S. universities before the turn of the century.

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第2题

1： Directions: Read the following texts and answer the questions which accompany them by c

hoosing A, B, C or D. Mark your answers on ANSWER SHEET 1. To produce the upheaval in the United States that changed and modernized the domain of higher education from the mid-1860' s to the mid-1880' s, three primary causes interacted. The mergence of a half-dozen leaders in education provided the personal force that was needed. Moreover, an outcry for a fresher, more practical, and more advanced kind of instruction arose among the alumni and friends of nearly all of the old colleges and grew into a movement that overrode all conservative opposition. The aggressive "Young Yale" movement appeared, demanding partial alumni control, a more liberal spirit, and a broader course of study. The graduates of Harvard University simultaneously rallied to relieve the University' s poverty and demand new enterprise. Education was pushing toward higher standard in the East by throwing off church leadership everywhere, and in the West by finding a wider range of studies and a new sense of public duty. The old-style. classical education received its most crushing blow in the citadel of Harvard University, where Dr. Charles Elliot, a young captain of thirty-five, son of a former treasurer of Harvard led the progressive forces. Five revolutionary advances were made during the five years of Dr. Elliot administration. They were the elevation and amplification of entrance requirements, the enlargement of the curriculum and the development of the elective system, the recognition of graduate study in the liberal arts, the raising of professional training in law, medicine, and engineering to a postgraduate level, and the fostering of greater maturity in student life. Standards of admission were sharply advanced in 1872 -1873 and 1876 -1877. By the appointment of a dean to take charge of student affairs , and a wise handling of discipline, the undergraduates were led to regard themselves more as young gentlemen and less as young"animals. One new course of study after another was opened up—science, music, the history of the fine arts, advanced Spanish, political economy, physics, classical philology, and international law. The passage mainly deals with______.

A.innovations in the United States' higher education in the late 1800s

B.Harvard University graduates' success

C.the development of Harvard University

D.the aggressive "Young Yale" movement

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第3题

Upheaval in Higher Education To produce the upheaval （剧变) in the United States that

Upheaval in Higher Education

To produce the upheaval (剧变) in the United States that changed and modernized the domain of higher education from the mid 1860's to the mid 1880's. three primacy causes interacteD．The emergence of a half dozen leaders in education provided the personal force that was needeD． Moreover. an outcry for a fresher, more practical, and more advanced kind of instruction arose among the alumni(校友)and friends of nearly all of the old colleges and grew into a movement that overrode (压倒) all conservative opposition. The aggressive "Young Yale" movement appeared, demanding partial alumni control, a more liberal spirit, and a broader course of study. The graduates of Harvard College simultaneously rallied (聚集)to relieve the college's poverty and demand new enterprise. Education was pushed toward higher standards in the East by throwing off church leadership every- where, and in the West by finding a wider range of studies and a new sense of public duty.

The old-style. classical education received its most crushing blow in the citadel of Harvard College, where Dr. Charles Eliot, a young captain of thirty-five, son of a former treasurer of Harvard, led the progressive forces. Five revolutionary advances were made during the first years of Dr. Eliot's administration. They were the elevation and amplification of entrance requirements, the enlargement of the curriculum and development of the elective system, the recognition of graduate study in the liberal arts, the raising of professional training in law, medicine, and the fostering of greater maturity in student life. Standards of admission were sharply advanced in 1872-1873 and 1876-1877. By the appointment of a dean to take charge of student affairs, and a wise handling of discipline, the undergraduates were led to regard themselves, more as young gentlemen and less as young animals. One new course of study after another was opened up: science, music, the history of the fine arts, advanced Spanish, political economy, physics, classical philology, and international law.

第 31 题 Which of the following is the author's main purpose in writing the passage？

A．To present the history of Harvard College and compare it with that of Yale University.

B．To criticize the conditions of the U.S. university in the 19th century.

C．To describe innovations in the U.S. higher education in the latter 1800's.

D．To introduce what was happening in major U. S. universities before the turn of the century

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第4题

Classical physics defines the vacuum as a state of absence :a vacuum is said to exist in a

region of space if there is nothing in it. In the quantum field theories that describe the physics of elementary particles, the vacuum becomes somewhat more complicated. Even in empty space, particles can appear spontaneously as a result of fluctuations of the vacuum. For example, an electron and a positron, or antielectron, can be created out of the void(空间).Particles created in this way have only a fleeting existence; they are annihilated(消亡) almost as soon as they appear, and their presence can never be detected directly. They are called virtual particles in order to distinguish them from real particles, whose lifetimes are not constrained in the same way, and which can be detected. So it is still possible to define the vacuum as a space that has no real particles in it.

One might expect that the vacuum would always be the state of lowest possible energy for a given region of space. If an area is initially empty and a real particle is put into it, the total energy, it seems, should be raised by at least the energy equivalent of the mass of the added particle. A surprising result of some recent theoretical investigations is that this assumption is not invariably tree. There are conditions under which the introduction of a real particle of finite mass into an empty region of space can reduce the total energy. If the reduction in energy is great enough, an electron and a positron will be instantly created. Under these conditions the electron and positron are not a result of vacuum fluctuations but are real particles, which exist indefinitely and can be detected. In other words, under these conditions the vacuum is an unstable state and can decay(衰)into a state of lower energy; that is one in which real particles are created.

The necessary condition for the decay of the vacuum is the presence of an intense electric field. As a result of the decay of the vacuum, the space permeated by such a field can be said to obtain an electric charge, and it can be called a charged vacuum. The particles that materialize in the space make the charge vacuum is likely to be found in only one place: in the immediate vicinity of a super heavy atomic nucleus(原子核) ,one with about twice as many protons as the heaviest natural nuclei known. A nucleus that large cannot be stable, but it might be possible to assemble one next to a vacuum for long enough to observe the decay of the vacuum. Experiments attempting to achieve this are now under way.

Which of the following titles best describes the passage as a whole？

A．The Vacuum: Its Fluctuations and Decay.

B．The Vacuum: Its Creation and Instability.

C．The Vacuum: A state of Absence.

D．Particles That materialize in the Vacuum.

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第5题

新古典宏观经济学（New Classical Macroeconomics)

新古典宏观经济学(New Classical Macroeconomics)

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第6题

Chemistry is ______ than physics for me.A．easyB．easierC．more easy