历年职称英语理工类A级-真题及答案(4)

下面有3篇短文，每篇短文后有5道题。请根据短文内容,为每题确定1个最佳选项。 第一篇

How the First Stars in the Universe Came into Existence How the first stars formed from this dust and gas has been a burning question for years，but a state-of-the-art computer simulation now offers the most detailed picture yet of how these first stars in the universe came into existence，researchers say．

The composition of the early universe was quite different from that of today，and the physics that governed the early universe were also somewhat simpler．Dr．Naoki Yoshida and colleagues in Japan and the U．S．incorporated these conditions of the early universe，sometimes referred to as the "cosmic dark ages，"to simulate the formation of an astronomical object that would eventually shine its light into this darkness．

The result is a detailed description of the formation of a protostar-the early stage of a massive primordial star of our universe，and the researchers'computer simulation，which has been called a "cosmic Rosetta Stone．"sets the bar for further investigation into the star formation process．The question of how the first stars evolved is so important because their formations and eventual explo-sions provided the seeds for subsequent stars to come into being． According to their simulation，gravity acted on minute density variations in matter，gases，and the mysterious"dark matter''of the universe after the Big Bang in order to form this early stage of a star-a protostar with a mass of just one percent of our sun．The simulation reveals how pre-stellar gases would have actually evolved under the simpler physics of the early universe to form this protostar．

Dr．Yoshida's simulation also shows that the protostar would likely evolve into a massive star capableof synthesizing heavy elements，not just in later generations of stars，but soon after the Big Bang．

"This geneal picture of star formation，and the ability to compare how stellar objects form in different time periods and regions of the universe，will eventually allow investigation into the originsof life and planets，"said Lars Hernquist，a Professor of Astronomy at Harvard University

and a coauthor of this latest report．"The abundance of elements in the universe has increased as stars haveaccumulated，"he says，"and the formation and destruction of stars continues to spread these ele． ments further across the universe．So when you think about it．a11 of the elements in our bodies originally formed from nuclear reactions in the centers of stars，long ago．"

Their simulation of the birth of a protostar in the early universe signifies a key step toward theambitious goal of piecing together the formation of an entire primordial star and of predicting the massand properties of these first stars of the universe．More powerful computers，more physical data，andan even larger range will be needed for further calculations and simulations，but these researchers hope to eventually extend this simulation to the point of nuclear reaction in．itiation-when a stellar ob． ject becomes a true star．

"Dr．Yoshida has taken the study of primordial star formation to a new level with this simulation，but it still gets us only to the halfway point towards our final goal．It is like laying the foundation of a skyscraper，"said Volker Bromm，Assistant Professor of Astronomy at the University of Tex． as，Austin and the author of a companion article．"We must continue our studies in this area to un-derstand how the initially tiny protostar grows，layer by layer，to eventually form a massive star．Buthere，the physics become much more complicated and even more computational resources are needed．"

31．According to the first two paragraphs，the early universe_______．

A．was governed by simpler physics B．got fewer stars shinning in it C．started over 13 billion years ago

D．was composed in a way similar to that of today 32．What can the state-of-the．art computer simulation tell us about?

A．How the Big Bang occurred about 13 billion years ago． B．How"cosmic dark ages"came into existence． C．How dust grains and gases were formed after the Big Bang．

D．How the first stars canle into being after the Big Bang．

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