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1. Icebergs are among nature's most spectacular（壮观的）creations , and yet most people have never seen one.A vague air of mystery envelops them.They come into being somewhere in faraway, frigid waters,amid thunderous noise and splashing turbulence,which in most case no one hears or sees. They exist only a short time and then slowly waste away（消融）just as unnoticed.
2. Objects of sheerest（最纯粹的）beauty they have been called. Appearing in an endless vaniety of shapes,they may be dazzlingly white,or they may be glassy blue,green or purple,tinted faintly on in darker hues.They are graceful, stately,inspiring in calm,sunlight seas.
3.But they are also called frightening and dangerous,and that they are一in the night,in the fog,and in storms.Even in clear weather one is wise to stay a safe distance away from them.Most of their bulk is hidden below the water,so their underwater parts may extend out far beyond the visible top.Also,they may roll over unexpectedly,churning the waters around them.
4.Icebergs are parts of glaciers that break off,drift into the water,float about awhile,and finally melt.Icebergs afloat today are made of snowflakes that have fallen over long ages of time.They embody snows that drifted down hundreds,or many thousands,or in some cases maybe a million years ago.The snows fell in polar region and on cold mountains,where they melted only a little or not at all,and so collected to great depths over the years and centuries.As each year's snow accumulation lay on the surface,evaporation and melting caused the snowflakes slowly to lose their feathery points and become tiny grains of ice.When new snow fell on top of the old,it too turned to icy grains.So blankets of snow and ice grains mounted layer upon layer and were of such great thickness that the weight of the upper layers compressed the lower ones.With time and pressure from above, the many small ice grains joined and changed to larger crystals,and eventually the deeper crystals merged into a solid mass of ice.
Paragraph 4___________
A:Formation of iceberg
B:Iceberg is beautiful
C:Color of iceberg
D:Iceberg is dangerous
E:Iceberg is mysterious
F:Classification of iceberg
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第三篇
A New Cause of Suffering
A conference on obesity（肥胖症）was recently held in Vienna. Two thousand experts
from more than fifty countries attended the conference.According to statistics,1.2 billion
people worldwide are overweight,and 250 million are too fat.Obesity is rapidly becoming a
new cause of suffering.
Professor Friedrich Hopichler of Salzberg said:"We are living in the new age but with
the metabolism（新陈代谢）of a stone-age man. I have just been to the United States. It is
really terrible. A pizza（比萨饼）shop is appearing on every corner. We have been
occuoied by fast food and Coca-Cola-ization."
Many of the experts stressed that obesity was a potential killer.Hopicnier saia:
"Eighty per cent of all diabetics（糖尿病人）are too fat,also fifty per cent of all patients with
high blood pressure and fifty per cent with fatty（脂肪的）tissue complaints. Ten per cent
more weight means thirteen per cent more risk of heart disease.Reducing one's weight by
ten oer cent leads to thirteen per cent lower blood pressure."
Another expert Hermann Toplak said that the state health services should improve their
financing of preventive programs,"The health insurance pays for surgery(such as
reducing the size of the stomach ) when the body-mass index（身体质量指数）is more than
40.That is equivalent to a weight of 116 kilograms for a height of 1.60 meters.One should
start earlier."
Toplak said that prevention should begin in school.“Child obesity has a close relation
with the time which children spend in front of TV sets."
Hermann Toplak suggested that more money should be spent on
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B:fat people.
C:preventive programs.
D:state health services. -
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Late-night Drinking
Coffee lovers,be careful. Having a quick “pick-me-up” cup of coffee late in the day will interrupt your sleep. As well as being a stimulant（兴奋剂）,caffeine interrupts the flow of melatonin（褪黑激素）,the brain hormone that sends people into a sleep.
Melatonin levels normally start to rise about two hours before bedtime. Levels then peak between 2 am and 4 am, before falling again.“It's the neurohormone（神经激素）that con-trols our sleep and tells our body when to sleep and when to wake,”says Maurice Ohayon of the Stanford Sleep Epidemiology Research Center at Stanford University in California. But researchers in Israel have found that caffeinated coffee halves the body's levels of this sleep hormone.
Lotan Shilo and a team at the Sapir Medical Center in Tel Aviv University found that six volunteers slept less well after a cup of caffeinated coffee than after drinking the same amount of decaf（脱咖啡因咖啡）.On average, subjects slept 336 minutes per night after drinking caffeinated coffee,compared with 415 minutes after decaf. They also took half an hour to drop off,twice as long as usual.
In the second phase of the experiment,the researchers woke the volunteers every three hours and asked them to give a urine（尿）sample. Shilo measured concentrations of a break-down product of melatonin. The results suggest that melatonin concentrations in caffeine drinkers were half those in decaf drinkers. In a paper accepted for publication in Sleep Medi-cine,the researchers suggest that caffeine blocks production of the enzyme（酶）that drives melatonin production.
Because it can take many hours to eliminate caffeine from the body. Ohayon recommends that coffee lovers switch to decaf after lunch.
The author mentions“pick-me-up” to indicate that______.
A: melatonin levels need to be raised
B: coffee is a stimulant
C: neurohormone can wake us up
D: caffeine can balance our brain hormone