pp阅读问题

sailing2003

PP阅读TEST2第98题目答案是C,但我觉得B也有问题啊

The closest a large asteroid has come to flying

by Earth occurred on March 22, 1989, when asteroid

1989 FC came within 430,000 miles of our planet.  

Astronomers did not detect asteroid 1989 FC until it

was already moving away from Earth.  Only then did

they notice a dramatic decrease in the asteroid's

motion against background stars.  The astronomers

failed to notice the approach, which must have been

on a near-grazing trajectory, because it came from

the direction of the Sun.  Also, the Moon was nearly

full, further hampering observations.

    The asteroid was about half a mile wide,

and though a collision with Earth would have been

catastrophic, a fluke of orbital geometry might have

lessened the impact a little.  The asteroid orbits the

Sun in the same direction and at almost the same

speed as Earth, completing a revolution in about

one year.  Therefore, its approach was rather slow

compared to other celestial objects.  However,

because of Earth's large size, the planet's

gravitational pull would have accelerated the asteroid

during its final approach.  If a collision had occurred,

the asteroid would have produced a crater five to ten

miles wide.

    Asteroid 1989 FC is one of only thirty similar

bodies that are capable of approaching Earth.  In

addition, several hundred to one thousand or more

asteroids wider than one-third of a mile are capable

of crossing Earth's orbit for a close encounter.  For

example, on December 8, 1992, a large asteroid called

Toutatis, which measured 2.5 miles long by

1.6 miles wide, flew within 2.2 million miles of Earth.

    Not one of the close encounters had been

anticipated by astronomers.  To avoid the danger

of an asteroid collision, the threatening body would first

have to be tracked by telescopes and radar

and its course plotted accurately so its orbit could be

determined precisely.  If an asteroid were found to be

on a collision course with Earth, astronomers could

provide timely warnings.  The rogue asteroid might

then be nudged out of its Earth-bound trajectory by

use of explosive devices.

98. The paragraph below is a summary  of the passage.  Click on the sentence in the paragraph that should NOT be included in the summary.

  (A) Theasteroid to most closely approach Earth in recorded history was 1989 FC.  

   (B)There may be over one thousand asteroids that are similar in size to asteroid 1989 FC.  

   (C)The most accurate way to measure the size of an asteroid is to observe its passage in front of a star.

   (D)Tracking asteroids and calculating orbits would possibly allow astronomers to prevent their collisions with Earth.  

[此贴子已经被作者于2005-6-12 12:42:22编辑过]

sailing2003

问题太简单了？呵呵，不好意思啊。

承影

有没有原文？

mikelyung

只有C 原文没提过,其他都题过

重剑无锋

请楼主提问的时候附上原文。这个……咳咳……斑竹网友们是不能把pp随身携带、有备无患的。

sailing2003

已经加上原文了。

原文中明确提到和1989 FC大小相近的小行星只有30颗啊，B好象也不对吧。