全世界最大的汽车生产国是（）。 A.中国 B.美国 C.德国 D.日本

操作系统是计算机系统的一种系统软件，它以尽量合理、有效的方式组织和管理计算机的【 】，并控制程序的运行，使整个计算机系统能高效运行。

风险评估是指（）。

A.采用适当的理论方法，结合过去类似风险发生的信息，分析发生损失的概率分布，定性评估风险可能造成的损失

B.主动控制风险、降低风险发生的可能性，减弱风险带来损失，进行风险防范，采用规避或转移风险的措施或自留部分风险等

C.按照某一种风险分类的方法，将可能发生的风险因素列出，进行初步的归纳分析

D.采用适当的理论方法，结合过去类似风险发生的信息，分析发生损失的概率分布，定量评估风险可能造成的损失

      After almost 30 years of arguing that a black hole swallows up everything that falls into it, British

astrophysicist (天体物理学家) Stephen Hawking moved backward last week.

      The world-famous writer of "Brief History of Time" said he and other scientists had got it wrong.  

     "I've been thinking about this problem for the last 30 years, and I think I now have the answer to it,"

said Hawking. "A black hole only appears to form but later opens up and set free information about

what fell inside. So we can be sure of the past and can predict the future."

      The findings could help solve the "black hole information paradox(似是而非的观点)", an important

puzzle in modern physics.

      A black hole is an area in space where matter is under such pressure that even light can not escape

from its gravitational pull(引力). But, exactly what happens there has long puzzled scientists.

      Black holes occur when a powerful star burns up its nuclear fuel and gravity forces it to break down

in on itself. The great weight of the star's outer layers moves in towards its center. The force of gravity

keeps nearly all light from escaping and nothing inside can be seen from the outside.

      The star actually disappears from the universe into a point of infinite density(高密度). That is a place

where the laws of general relativity that govern space and time break down.

     Hawking has devoted most of his life to studying these questions.

     At the beginning, cosmologists believed the holes were like a "universal vacuum (真空) cleaner",

sucking up everything in their path.

      Hawking revolutionized the study of black holes when he proved, in 1976 that, under the strange

rules of quantum physics(量子物理), when black holes form they send out energy and lose mass in the

process.

      In thinking up this so-called "Hawking radiation", the Cambridge mathematician also created one of

the biggest puzzles in physics.

      These particles (粒子), he said, contained no information about what has been occurring inside the

black hole, or how it formed. Under his theory, once the black hole disappears, all the information within

it is lost.

1. What's the importance of Hawking's new findings?    

A. They could help solve the puzzle about black holes.

B. They has solved the mystery of "black holes".

C. We can now know what is going on inside "black holes".

D. Scientists have already predicted the future of "black holes" now.

2. What's the meaning of the underlined word "cosmologist" (in Paragraph 9)?  

A. A person who studies the universe and its origin and development. 

B. A person who studies the stars and their development.

C. A person who travels in a spacecraft.

D. A person who studies the position of the stars and the movements of the planets.

3. Which of the following is TRUE?  

A. Hawking has now studied black holes for more than 40 years.

B. During the course of the black hole's forming the enormous weight of the star's center

moves into the outer layers.

C. Almost nothing can escape from the gravitational pull of the black hole.

D. Scientists have been thinking the black hole contains no information.

4. What would be the best title for the passage?  

A. The Formation of the Black Hole 

B. Black Hole Information Paradox

C. Black Hole Mystery

D. The Cause of the Black Hole

1937年7月7日，日军炮轰（），中国守军奋起抵抗，史称“（）”，标志着中国全民族抗战开始，标志着日本全面侵华开始。

基坑槽盒管沟回填土时，下方不得有人，所使用的打夯机等要坚持电器线路，防止（），停机时要关闭电闸。

A.漏电

B.触电

C.漏水