Prep2012_Pack1_RC(题目版)(4)

The passage suggests that modern multinationals differ from early chartered trading companies in that

A. the top managers of modern multinationals own stock in their own companies rather than

simply receiving a salary

B. modern multinationals depend on a system of capitalist international trade rather than on

less modern trading systems

C. modern multinationals have operations in a number of different foreign countries rather

than merely in one or two

D. the operations of modern multinationals are highly profitable despite the more stringent

environmental and safety regulations of modern governments

E. the overseas operations of modern multinationals are not governed by the national

interests of their home countries

PREP2012-Pack1-RC-002

A meteor stream is composed of dust particles that have been ejected from a parent comet at a variety of velocities. These particles follow the same orbit as the parent comet, but due to their differing velocities they slowly gain on or fall behind the disintegrating comet until a shroud of dust surrounds the entire cometary orbit. Astronomers have hypothesized that a meteor stream should broaden with time as the dust particles’ individual orbits are perturbed by planetary gravitational fields. A recent computer-modeling experiment tested this

hypothesis by tracking the influence of planetary gravitation over a projected 5,000-year period on the position of a group of hypothetical dust particles. In the model, the particles were randomly distributed throughout a computer simulation of the orbit of an actual meteor stream, the Geminid. The researcher found, as expected, that the computer-model stream broadened with time. Conventional theories, however, predicted that the distribution of

particles would be increasingly dense toward the center of a meteor stream. Surprisingly, the computer-model meteor stream gradually came to resemble a thick-walled, hollow pipe. Whenever the Earth passes through a meteor stream, a meteor shower occurs. Moving at over 1,500,000 miles per day around its orbit, the Earth would take, on average, just over a day to cross the hollow, computer-model Geminid stream if the stream were 5,000 years old. Two brief periods of peak meteor activity during the shower would be observed, one as the Earth entered the thick-walled “pipe" and one as it exited. There is no reason why the Earth should always pass through the stream's exact center, so the time interval between the two bursts of activity would vary from one year to the next.

Has the predicted twin-peaked activity been observed for the actual yearly Geminid meteor shower? The Geminid data between 1970 and 1979 show just such a bifurcation, a secondary burst of meteor activity being clearly visible at an average of 19 hours (1,200,000 miles) after the first burst. The time intervals between the bursts suggest the actual Geminid stream is about 3,000 years old.

PREP2012-Pack1-RC-002-01 VRC07544-01 Hard

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