职称英语考试理工类(B级)试题及答案

02年职称英语考试理工类(B级)试题及答案6

第三篇 Black Hoies

What is a black hole?Well，it’s difficult to answer this question，since the terms we

normally use to describe a scientific phenomenon are inadequate here．Astronomers

and scientists think that a black hole is a region of space(not a thing)into which matter

has fallen and from which nothing can escape-not even light．So we can’t see a black

hole．A black hole exerts(施加)a strong gravitational(重力的)pull and yet it has no

matter．It is only space-or so we think. How can this happen?

The theory is that some stars explode when their density increases to a particular

point；they”collapse”and sometimes a supernova(超新星)occurs．The collapse of a star

may produce a

“White Dwarf (白矮星)”of a”neutron star”一a star whose matter is so dense that lt

continually shrinks by the force of its own gravity．But if the star is very large this

process of shrinking may be so intense that a black hole results．Imagine the earth

reduced to the size of a marble，but still having the same mass and a stronger

gravitational pull，and you have some idea of the force of a black hole．Any matter

near the black hole is sucked in．It is impossible to say what happens inside a black

hole．

Our space and time laws don’t seem to apply to objects in the area of a black

hole.Einstein’s relativity theory is the only one that can explain such

phenomena．Einstein claimed that matter

and energy are interchangeable．so that there is no”absolute”time and space. There

are no constants at all, and measurements of time and space depend on the position of

the observer-they are relative．Einstein’s theory provided a basis for the idea of black holes before astronomers started to find some evidence for their existence．It is only

recently that astronomers have begun

specific research into black holes．

The most convincing evidence of black holes comes from research into binary(由两部分组成的) star systems．In some binary star systems，astronomers have shown

that there is an

invisible companion star,a”partner”to the one which we can see in the sky．There is

one star,called by its catalogue number HDE 226868．which must have a partner．This

partner star,it seems．has a mass ten or twenty times greater than the sun-yet we can’t

see it．Matter from HDE 226868 is being dragged towards this companion star．Could

this invisible star,which exerts such a great force，be a black hole?Astronomers have

evidence of a few other stars too，which might have black holes as companions．

4l Which of the following does NOT fit the definition of the black hole?

A The black hole is a region of space．

B The black hole sucks in any object that passes by it．

C The black hole is visible through an infrared telescope．

D The black hole has no matter．

42 Why does the author put”neutron star”in quotation marks?

A It is a special term of astronomy．

B It is an inventedterm．

C He is quoting an authority．

D He is using the term ironically．

43 What leads to the formation of a black hole?

A The structure of a star． B A collision between two stars．

C The attraction of two large stars．

D The shrinking of a large star by its own gravitational force.

44 According to Einstein’s theory,objects in the area of a black hole

A are gathered in its center．

B strike against one another frequently．

C do not have absolute space．

D are relatively brighter．

45 We learn from this passage that

A the sun is the heaviest star in the universe．

B a star in the sky might have an invisible partner．

C two black holes are dragged towards each other．

D the mass of a star is equal to that of its companion.