The dark regions in the starry night sky are not
pockets in the universe that are devoid of stars as
had long been thought. Rather, they are dark because
Line of interstellar dust that hides the stars behind it.
5 Although its visual effect is so pronounced, dust is
only a minor constituent of the material, extremely
low in density, that lies between the stars. The average density of interstellar material in the vicinity of our Sun is 1,000 to 10,000 times less than the best terrestrial
10 laboratory vacuum. It is only because of the enormous interstellar distances that so little material per unit of
volume becomes so significant. Optical astronomy
is most directly affected, for although interstellar gas
is perfectly transparent, the dust is not. (125 words)
It can be inferred from the passage that it is
because space is so vast that
(A) little of the interstellar material in it seems substantial
(B) normal units of volume seem futile for measurements
of density
(C) stars can be far enough from Earth to be obscured
even by very sparsely distributed matter
(D) interstellar gases can, for all practical purposes, be
regarded as transparent
(E) optical astronomy would be of little use even if no
interstellar dust existed
答案是c 为什么a不对呢？作者: gonggong1 时间: 2012-7-29 19:52:54
A说反了, LZ 一定是 LITTLE OF 理解反了 作者: zy3854 时间: 2012-7-29 22:09:14