填空题
{{B}}Part A Spot Dictation{{/B}}
Directions:
In this part of the test, you will hear a passage and read the same
passage with blanks in it. Fill in each of the blanks with the word or words you
have heard on the tape.
It streaked across the sky in a warm March evening last year,
then {{U}}(1) {{/U}} a street in the small town of Monahans, Texas. When
seven boys quit their basketball game to {{U}}(2) {{/U}} the damage,
they found a shiny, black grapefruit-size rock nestled in the asphalt. {{U}}
(3) {{/U}} traveled quickly in newspapers and on TV. The next day, NASA
scientist Everett Gibson arrived and took the meteorite, later named Monahans
1998, back to a lab in Houston. There researchers {{U}}(4) {{/U}} the
extraterrestrial rock with a hammer and chisel. To their surprise, they smack
water. A team led by Michael Zolensky of the Johnson Space Center reports
{{U}}(5) {{/U}} in the current issue of the journal Science. It's the
first time anyone has found liquid water {{U}}(6) {{/U}} from space-and
a tantalizing suggestion that {{U}}(7) {{/U}}.
Meteorites containing water are probably not {{U}}(8) {{/U}} ,
Zolensky says. But by the time researchers get their hands on the rocks,
minerals that trap the water {{U}}(9) {{/U}} away, and the water has
evaporated. "Worse, some researchers destroy the aqueous evidence by cutting
meteorites open with rock saws and water. I'm betting this isn't {{U}}(10)
{{/U}}; it's just that people have been {{U}}(11) {{/U}} their
meteorites," Zolensky says.
Of course, Zolensky's team did get
a bit lucky. Monahans 1998 was safe in their lab less than two days after it hit
Earth, so they examined {{U}}(12) {{/U}}. The scientists were intrigued
to find vivid purple crystals of halite inside the meteorite, since halite is a
salt {{U}}(13) {{/U}} usually formed from liquid water. Even more
curious were the hundreds of tiny bubbles {{U}}(14) {{/U}} in the halite
crystals. Zolensky's team analyzed the bubbles by shining {{U}}(15)
{{/U}} through them and confirmed they were made of salty brine.
By dating the halite, Zolensky's team found the water trapped inside it
formed at least 4.5 billion years ago, back when most scientists believe
{{U}}(16) {{/U}} was born. That means the briny relic may help
researchers learn about the gaseous-nebula that {{U}}(17) {{/U}} our sun
and planets.
But how did the meteorite get wet? One possibility
is that a passing comet {{U}}(18) {{/U}} the rock, dropping off a load
of liquid water. Or the rock might have chipped off an asteroid that holds pools
of fluid. Zolensky's team still needs to study whether the water comes from our
own solar system. One thing is certain, however: the Monahans meteorite will
fuel {{U}}(19) {{/U}} extraterrestrial life. "Water is a life-giver, so
if you want to study where life came from in the solar system, you have to
{{U}}(20) {{/U}}," Zolensky says. A wet rock from space doesn't mean
little green men are coming soon to a planet near you, but it does raise hopes
that we're not alone in the universe.