After almost 30 years of arguing that a

题型:阅读理解

问题:

      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

考点:科教类阅读
题型:阅读理解

下列可以适用代理的行为是()。

A.买卖

B.立遗嘱

C.接受继承

D.债务履行

E.收养子女

题型:阅读理解

以下哪项不是妊娠期糖尿病的并发症()

A.易并发子痫前期

B.易发生泌尿生殖系统感染

C.肝功能损害

D.易发生难产

E.易发生产后出血

题型:阅读理解

八一南昌起义的主要领导人有:(),(),(),(),()。

题型:阅读理解

25℃、101 kPa条件下,反应2N2O5(g)=4NO2(g)+O2(g) △H=+56.7 kJ/mol 能自发进行的原因[ ]

A. 是吸热反应

B. 是放热反应

C. 是熵减小的反应

D. 是熵增效应大于热效应

题型:阅读理解

男性患者,60岁,患有颈椎管狭窄,行颈椎后路手术,手术时使用局麻强化。

在局麻药内加肾上腺素的目的为

A.防止麻醉后血压下降

B.防止麻醉后心率减慢

C.使血管收缩,减慢麻醉药吸收,延长作用时间

D.防止手术野大出血

E.调整自主神经功能

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