第三篇 "Life Form Found" on Saturn's Titan
- [, M7 q& z$ P' q( v% q2 ] Scientists say they have discovered hints of alien life on the Saturn's moon. The discovery of a sort of life was announced after researchers at the US space agency,NASA,analyzed data from spacecraft Cassini,which pointed to the existence of methane-based form of life on Saturn's biggest moon.
0 @; J7 `! n5 Z$ e' j! I Scientists have reportedly discovered clues showing primitive alien beings are"breathing" in Titan's dense atmosphere filled with hydrogen.# U! ?2 _9 S; J# {: x
They argue that hydrogen gets absorbed before hitting Titan's planet-like surface covered with methane lakes and rivers. This,they say,points to the existence of some"bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth.0 h- s% t ]: L$ A! E
"We suggested hydrogen consumption because it's the obvious gas for life to consume on Titan,similar to the way we consume oxygen on Earth,"says NASA scientist Chris McKay."If these signs do turn out to be a sign of life,it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth."; k: B6 x0 _% q/ ^
To date,scientists have not yet detected this form of life anywhere,though there are liquid-water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Farenheit),a methanebased organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan's surface and much too cold to support life as we know it.
: ^" C9 K+ N: ~5 F n7 A Scientists had expected the Sun's interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan's surface. But Cassini detected no acetylene on the surface.
3 M4 W* l, R; d2 [ _- g The absence of detectable acetylene on the Titan's surface can very well have a non-biological explanation,said Mark Allen,a principal investigator of the NASA Titan team.& o4 S. G8 s2 ?, Q/ X. z
"Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed,"Allen said. "We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process,without biology,can explain these results."* K% ]& S8 \, w& Y F, M* U7 U3 \
41 .What do scientists claim to have found about Saturn?
7 r& \- \! W4 o A. Water-based life on it.
& [" ^" v% n* f( H D0 m B. Methane-based life on its biggest moon.
1 J. z0 G. A: l _$ ^( @, D C. A new moon moving around it. ! i: s7 g9 H. V8 q
D. Earthlike life on its biggest moon.5 F, C9 r. |. T5 K
42. Which of the following statements about Titan is true?
- q ~6 m& G1 e' } B A. It is as large as the Earth.8 Q l, l; ?4 l- R& i0 e: O
B. There is acetylene on its surface.
. L, D: f0 Z, f u* L9 y& c+ @ C. Water on it acts as a life supporting medium.
2 L# M) E- C; k) ^7 T _ D. Hydrogen consumption is reported to be on it.
* p) [5 G. ~3 G 43. The expression "this form of life" in paragraph 5 refer to?6 M- V3 h7 {4 c0 c% h% t
A. Water-based life.8 {( J1 C% f: @7 D: i! @3 T
B. oxygen-based life.
! @* g3 S% `6 I# u/ a, k4 r- m C. Methane-based life.( K, @4 L1 _! I5 R* f( A. F9 `) P
D. Liquid-based microorganisms.
1 m |; C( `% ~# `+ r: M 44. It can be inferred from Mark Allen’s address that
! ~/ I9 r3 `* C A. Scientists are trying to confirm these is life on Titan.# a% ~8 H; }' K& F. H4 j9 K1 D
B. Scientists agree that a chemical process is a convincing explanation.& B9 V) g9 g0 z* L
C. Scientists share the opinion that a biological explanation is reasonable.
1 M) Q' a. _6 H, ]/ P V D. Scientists are arguing over whether there is life on Titan.
: g1 u; d: r+ d 45. Which of the following can replace the title of this passage?
1 ^1 @" P) @ I$ k% B A . A different Life Form, a Possibility.
9 G" ?4 O: Z% R0 _ B. Earthlike Living Beings Found on Titan.
6 \0 X; J; Z S, H( C" [ C. Finding of One More Moon of Saturn’s.+ M& U: m4 v, m. ?# i5 H9 G7 s
D. Titan, a New Satellite Discovered. 2 k+ g, q% Y- x- y8 ?& ]
" V) P8 z. U3 _9 b$ f/ b% u, f. p/ e
参考答案: ACDBA) `+ x2 S+ M& D) k
Voice Your Opinion: Change Is Needed in Youth Sports/ v& q& ?* o. |% A
Everywhere you look, you see kids bouncing a basketball or waving a tennis racquet (网球拍). And these kids are getting younger and younger. In some countries, children can compete on basketball, baseball, and volleyball teams starting at age nine. (46) And swimming and gymnastics classes begin at age four, to prepare children for competition.
& n) C! B5 Q$ q It’s true that a few of these kids will develop into highly skilled athletes and may even become members of the national Olympic teams. (47) This emphasis on competition in sports is having serious negative effects.
3 m, V2 O7 w4 \$ F Children who get involved in competitive sports at a young age often grow tired of their sport. Many parents pressure their kids to choose one sport and devote all their time to it. (48) But 66 percent of the young athletes wanted to play more than one sport-for fun.3 Z W# u# d- n# e
Another problem is the pressure imposed by over-competitive parents and coaches. Children are not naturally competitive. In fact, a recent study by Paulo David found that most children don’t even understand the idea of competition until they are seven years old. (49)
# B6 k4 I; k+ Z3 L* v) W2 l& q The third, and biggest, problem for young athletes is the lack of time to do their homework, have fun, be with friends—in short, time to be kids. When they are forced to spend every afternoon at sports practice, they often start to hate their chosen sport. A searchers found that 70 percent of kids who take part in competitive sports before the of twelve quit before they turn eighteen. (50) Excessive competitive away all the enjoyment.
- b# z, O$ E, u; P Need to remember the purpose of youth sports – to give kids a chance to have developing strong, healthy bodies.' a$ P2 K' |; A
A.But what about the others, the average kids?
" D& }0 q' U7 F& ?9 L$ p# F B.The youth soccer organization has teams for children as young as five.$ A: Q2 p' |* @& a2 K, z" o
C.A survey found that 79 percent of parents of young athletes wanted their children concentrate on one sport.
! q. |! M2 g4 X z0 i. F1 x D.Very young kids don’t know why their parents are pushing them so hard.
1 x" c' r4 {" z4 K E.Sports for children have two important purposes.
2 T& @2 s6 [) E F.Many of them completely lose interest in sports. % L! Q3 j- R% ~+ c) \
1 T# T: o* M/ E6 B+ m9 H5 f 参考答案:ACFEB |