2021年 甘肃 职称英语(理工)如何报名

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第三篇

The Sahara

The name Sahara derives from the Arabic word for"desert"or"steppe".At 3.5 million square miles,
an area roughly the size of the United States,the Sahara Desert in northern Africa is the largest desert in the
world.It spans the continent from the Atlantic Ocean to the Red Sea.Daytime temperatures can reach as high
as 130°F.The humidity sometimes gets into the teens.But it can also be as low as 2.5 percent,the lowest in
the world.Most of the Sahara receives less than five inches of rain per year,while large areas sometimes have
no rainfall at all for years.
At the heart of the Sahara is the landlocked north African country of Niger. Here the sand dunes can be
100 feet tall and several miles long.Here sand plains stretch over an area larger than Germany where there is
neither water nor towns.Yet sitting in the midst of the surrounding desert is the town of Bilma. Suddenly there
are pools of clear water. Surprisingly,there are groves of date palms.Underground water resources,or oases,
sufficient to support irrigated agriculture are found in dry stream beds and depressions.Irrigation ditches run
off a creek to water fields.Corn,cassava,tea,peanuts,hot peppers,and orange,lime,and grapefruit trees grow
in these fields.Donkeys and goats graze on green grass.
The Sahara of Niger is still a region where you can see a camel caravan of 500 camels tied together in
loose lines as long as a mile,traveling toward such oasis towns.There a caravan will collect life-sustaining
salt,which is mined from watery basins,and transport it up to 400 miles back to settlements on the edges of
the desert.The round trip across the vast sands takes one month.

In this passage"caravan"means_______.
A:traveling circus
B:group traveling together through difficult country
C:railroad train
D:a small,fast sailing ship

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Learn about Light
1 .Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophers believed that light was made up of countless,tiny particles that enter the human eye and create what we call vision. However,Empedocles and a Dutch scientist named Christian Huygens believed that light was like a wave. According to them,light spread out and travelled like a straight line. This theory was accepted during the 19th century.
2 .In 1905,Albert Einstein published a research paper in which he explained what is re-ferred to as the photoelectric effect. This theory explains that particles make up light.The particles Einstein was referring to are weightless bundles（束）of electromagnetic（电磁）energy called photons（光子）.Today,scientists agree that light has a dual（二重）nature一it is part particle and part wave. It is a form of energy that allows us to see things around us.
3 .Things that give off light are known as sources of light. During the day,the primary source of light is the sun. Other sources of light include stars,flames,flashlights,street lamps and glowing gases in glass tube.
4 .When we draw the way light travels we always use straight lines. This is because nor-mally light rays travel in a straight line. However,there are some instances that can change the path and even the nature of light. They are reflection,absorption,interference（干扰）, etc.
5 .Physicists have attempted to measure the speed of light since the early times. In 1849, Hippolyte Fizeau conducted an experiment by directing a beam of light to a mirror located kilometers away and placed a rotating cogwheel（旋转齿轮）between the beam and the mirror. From the rate of rotation of the wheel,number of wheel's teeth and distance of the mirror,he was able to calculate that the speed of light is 313 million meters per second. In a vacuum（真空）,however,the speed of light is 299,792,458 meters per second. This is about a million times faster than the speed of an airplane.

Paragraph 2______
A: How Is the Nature of Light Explained Today?
B: What Are Sources of Light?
C: How Did Physicists Measure the Speed of Light?
D: How Does Light Travel?
E: How Did People Think of Light Years Ago?
F: What Causes a Shadow?

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The Cold Places
The Arctic is a polar region.It surrounds the North Pole.
Like Antarctica,the Arctic is a land of ice and snow.Antarctica holds the record for a low temperature reading-125 degrees
Fahrenheit below zero. Reading of 85 degrees below zero is common in both the Arctic and Antarctica.Winter temperatures average 30 degrees below zero in the Arctic .At the South Pole the winter average is about 73 degrees below zero.
One thing alone makes it almost impossible for men to live in Antarctica and in parts of the Arctic .This one thing is the low temperature-the killing chill of far North and the polar South.
To survive,men must wear the warmest possible clothing. They must build windproof shelters .They must keep heaters going at all times.Not ever for a moment can they be unprotected against the below-zero temperatures.
Men have a way of providing for themselves.Polar explorers wrap themselves in warm coats and furs .The cold makes life difficult. But the explorers can stay alive.
What about animals?Can they survive?Do we find plants?Do we find life in the Arctic and in Antarctica?Yes,we do. There is life in the oceans.There is life on land.
Antarctica,as we have seen,is a cold place indeed.But this has not always been the case.
Expedition scientists have discovered that Antarctica has not always been a frozen continent. At one time the weather in Antarctica may have much like our own.
Explorers have discovered coal in Antarctica. This leads them to believe that Antarctica at one time was a land of swamps and forests.Heat and moisture must have kept the trees in the forests alive.

The lowest temperature that man has ever known was recorded in Antarctica.
A:.Right
B: Wrong
C: Not mentioned