In July of 1994, an astounding series of events took place. The world anxiously
; k6 y" C% b. r2 A c: e4 B4 n watched as, every few hours, a hurtling chunk of comet plunged into the atmosphere of$ J" W- h. H1 k8 l, t
Jupiter. All of the twenty-odd fragments, collectively called comet Shoemaker-Levy 9
1 V% I) n+ G( ^5 A Line after its discoverers, were once part of the same object, now dismembered and strung out; I" _4 v Y1 U. q; h/ ?7 T0 d
(5) along the same orbit. This cometary train, glistening like a string of pearls, had been first
* y% y( T0 e y, l$ j! e5 f4 ~ glimpsed only a few months before its fateful impact with Jupiter, and rather quickly
$ D# V# _) G2 _- b1 f scientists had predicted that the fragments were on a collision course with the giant: \$ F1 W: L* D. J/ w9 x0 t/ A
planet. The impact caused an explosion clearly visible from Earth, a bright flaming fire
+ x6 f1 S: A N that quickly expanded as each icy mass incinerated itself. When each fragment slammed& s6 n. |0 {% C. }% g
(10) at 60 kilometers per second into the dense atmosphere, its immense kinetic energy was
. d0 {. O9 v9 ` o" a1 F) S transformed into heat, producing a superheated fireball that was ejected back through the- b2 X3 Q- C% l2 g
tunnel the fragment had made a few seconds earlier. The residues form these explo-$ ~, ~% Z' K8 c
sions left huge black marks on the face of Jupiter, some of which have stretched out to
. k7 A" E1 s$ P) z- d from dark ribbons.
5 @ y6 H0 A9 {0 x! l! t' [9 K F3 l7 @ (15) Although this impact event was of considerable scientific importance, it especially piqued/ B" N- B/ x* `- d, N2 v
public curiosity and interest. Photographs of each collision made the evening television
9 Z" x/ g3 w& V newscast and were posted on the Internet. This was possibly the most open scientific
4 P4 b& j& p5 {1 A0 f! b4 U endeavor in history. The face of the largest planet in the solar system was changed before+ v: g: [4 \. p& K
our very eyes. And for the very first time, most of humanity came to fully appreciate the
; y6 v% C- g2 H' _' i$ T (20) fact that we ourselves live on a similar target, a world subject to catstrophe by random
- L; `7 [1 q1 c6 l/ @/ {+ U1 j0 g, U assaults from celestial bodies. That realization was a surprise to many, but it should not
. U8 H9 n7 Z4 `% h3 g/ j have been. One of the great truths revealed by the last few decades of planetary explo-
8 f. B9 x6 @0 t# h. b ration is that collisions between bodies of all sizes are relatively commonplace, at least in1 j. U9 |& q- J
geologic terms, and were even more frequent in the early solar system.
) G L/ \4 E! g* ^ 3. The author compares the fragments of comet Shoemaker-Levy 9 to all of the following EXCEPT/ E. P4 S: @/ p* y# h
(A) a dismembered body# Q7 o z" h( D! Q
(B) a train, y5 i/ }0 q, @: H% y
(C) a pearl necklace' e% k1 Z: m9 A: ^( T$ `6 [
(D) a giant planet
/ f- W" A8 i9 \5 n# l J 答案:D
8 ]* Y/ ^% [0 |4 m- b By far the most important United States export product in the eighteenth and
9 h* o4 F; G4 Z" h9 d# D nineteenth centuries was cotton, favored by the European textile industry over flax or
5 ~+ l @% z. O) [8 x+ Z, g, H* y ~ wool because it was easy to process and soft to tile touch. Mechanization of spinning and
! c# m9 |! }9 a Line weaving allowed significant centralization and expansion in the textile industry during
?) A7 h2 M M# n Q; h1 j- V (5) this period, and at the same time the demand for cotton increased dramatically. American, d7 K( S! ]0 Z4 {4 T
producers were able to meet this demand largely because of tile invention of the cotton8 O- H1 K+ U; O. t* B
gin by Eli Whitney in 1793. Cotton could be grown throughout the South, but separating
( z2 X- `1 E" ?4 k- z the fiber—or lint—from the seed was a laborious process. Sea island cotton was% y5 R3 ?0 O3 O# ^
relatively easy to process by hand, because its fibers were long and seeds were" L. _* C& Y- z* G# t9 P
(10) concentrated at the base of the flower, but it demanded a long growing season, available
7 M* [! p& W2 z) Z5 _ only along the nation's eastern seacoast. Short-staple cotton required a much shorter
1 P/ V- z i6 |5 q" Z growing season, but the shortness of the fibers and their mixture with seeds meant that a
7 Z' |4 p7 w5 y* j0 K worker could hand-process only about one pound per day. Whitney's gin was a hand-
; D3 n* V6 Y5 f! c3 o- T powered machine with revolving drums and metal teeth to pull cotton fibers away from
, D& h- l6 H t( f, k7 R! a (15) seeds. Using the gin, a worker could produce up to 50 pounds of lint a day. The later% W& G, ?7 Z/ F
development of larger gins, powered by horses, water, or steam, multiplied productivity
1 E$ f( ~* B: r further.3 G' P$ a# r5 b A7 N- w ~: ?
The interaction of improved processing and high demand led to the rapid spread of
9 b G& ]3 E: ~. U( u0 W the cultivation of cotton and to a surge in production. It became the main American& d# @/ R7 P# J1 u0 z& k8 m
(20) export, dwarfing all others. In 1802, cotton composed 14 percent of total American) l& m( Q( N2 O# | N! u
exports by value. Cotton had a 36 percent share by 1810 and over a 50 percent share in
" N5 f2 }. E; n e! ?, m0 c 1830. In 1860, 61 percent of the value of American exports was represented by cotton.: V7 u. C8 G- Y! O- i
In contrast, wheat and wheat flour composed only 6 percent of the value of American
; `- H$ a3 U. M: {5 m8 d exports in that year. Clearly, cotton was king in the trade of the young republic. The
2 i' J( |* z3 g (25) growing market for cotton and other American agricultural products led to an
; R/ ?, W# {. c8 x unprecedented expansion of agricultural settlement, mostly in the eastern half of the
0 L0 t% Z& Q: N& b4 Y5 u United States—west of the Appalachian Mountains and east of the Mississippi River.
# z1 v' Y# }! b8 I 3. All of the following are mentioned in the passage as reasons for the increased demand for cotton EXCEPT0 x6 d+ z8 ?3 g+ W* p& k O" S
(A) cotton's softness
" w6 r" s& U$ W2 ? j9 T (B) cotton's ease of processing; |" D; ~: A7 A+ h' Z! g* x2 V& w( C- Z& g* w
(C) a shortage of flax and wool$ g4 `8 J( p7 L4 Z3 h1 j
(D) the growth that occurred in the textile industry.
( Q' P5 e1 T- _8 K/ J' B" m2 S: P 答案:C |