[求助]1997年阅读题第10题

quanner

Question 9-19

  Stars may be spheres, but not every celestial天上的 object is spherical. Objects in the universe show a variety of shapes: round planets (some with rings), tailed comets, wispy cosmic gas and dust clouds, ringed nebulae, pinwheel-shaped spiral galaxies, and so on.列举
                But none of the shapes on this list describes the largest single entities in the universe. These are the double radio sources, galaxies with huge clouds of radio emission that dwarf使变矮小 the visible galaxies, sometimes by a factor of a hundred or more. Stretching over distances greater than a million light-years, these radio-emitting regions resemble twin turbulent gas clouds, typically forming dumbbell-like shapes with the visible galaxy (when it is visible) in the center.

  These double radio sources逆向指代 present astronomers with a puzzle. Their radio emission arises from the synchrotron同步加速器 process, in which electrons accelerated to nearly the speed of light move through magnetic fields. However, in view of the rate at which the radio sources emit energy, they should disappear in a few million years as their electrons slow down and cease producing radiation. Somehow new electrons must be continually accelerated to nearly the speed of light, otherwise, by now almost none of the double radio sources would be observed.

  With the advent of high-resolution radio interferometers during the late 1970's, part of the answer became clear: the electrons are produced in jets that are shot out in opposite directions from the center of galaxy. Remarkably narrow and highly directional, the jets move outward at speeds close to the speed of light. When the jets strike the highly rarefied gas that permcales intergalactic space, the fast-moving electrons lose their highly directional motion and form vast clouds of radio-emitting gas.

  Cosmic jets have ranked among the hottest topics of astronomical research in recent years as astronomers strive to understand where they come from. Why should a galaxy eject matter at such tremendous speeds in two narrow jets? And why are such jets not seen in the Milky Way?

 

DC10.    The word "entities" in line 4 is closest in meaning to

(A)
                factors

(B)  processes

(C)
                objects

(D)
                puzzles

 

我觉得选C,怎么是D呢?

entity 就是实体的意思啊

 

enjoylife517

估计又是参考答案给错了，entity的意思C比较相近。

quanner

谢谢enjoylife517

大家答案都是网上下的吗

我都是从网上下的

有那么不可靠吗?!

enjoylife517

网上的答案有些也是错的，大家发现错了之后，也没有一个比较权威的版本再修改过来，所以也就一直保持着原样。

以前我记得有个新版本的，一下子找不到了。你有问题就贴出来好了。大家也可以讨论。

quanner

好的