The wish that shows birds to begin their journeys, and the highly exact feeling of direction shown by
traveling birds, stay among the most puzzling mysteries of science. The Arctic tern and the golden plover are
two examples of these unusual birds.
In the north during the springtime, traveling birds return to the Arctic (北极) from southern areas.
The longest journey is made by the unbelievable Arctic tern. This amazing bird is no larger than a crow (a
kind of bird) , but its body surface (outside) is more updated. The tern is called the long-distance champion
of the bird world, often traveling 23,000 miles a year between West Africa and the Arctic. Such journeys
take weeks, with stops for food and rest.
There are no rests, however, for the golden plover, a non-stop flyer among Arctic birds. The plover"s
journey is like that of a land plane over water, since the plover cannot land on the water to rest. Without
stopping, the golden plover flies 2,000 miles from Hawaii to Alaska or from South America to Nova Scotia
and northern Canada. This little bird (only eleven inches) is fat and strong when traveling north, but is thin
and weak when it arrives after fighting ocean winds for sixty or more hours.
B. 神秘
C. 机密
D. 隐秘
How Long Can People Live?
She took up skating at age 85, made her first movie appearance at age 114, and held a concert in the
neighborhood on her 121st birthday.
When it comes to long life, Jeanne Calment is the world"s recordholder. She lived to the ripe old age
of 122. So is 122 the upper limit to the human life span (寿命)? If scientists come up with some sort of pill
or diet that would slow aging, could we possibly make it to 150-or beyond?
Researchers don"t entirely agree on the answers. "Calment lived to 122, so it wouldn"t surprise me if
someone alive today reaches 130 or 135," says Jerry Shay at the University of Texas.
Steve Austad at the University of Texas agrees. "People can live much longer than we think," he says.
"Experts used to say that humans couldn"t live past 110. When Calment blew past that age, they raised the
number to 120. So why can"t we go higher?"
The trouble with guessing how old people can live to be is that it"s all just guessing. "Anyone can make
up a number," says Rich Miller at the University of Michigan. "Usually the scientist who picks the highest
number gets his name in Time magazine."
Won"t new anti - aging techniques keep us alive for centuries? Any cure, says Miller, for aging would
probably keep most of us kicking until about 120. Researchers are working on treatments that lengthen the
life span of mice by 50 percent at most. So, if the average human life span is about 80 year, says Miller,
"adding another 50 percent would get you to 120."
So what can we conclude from this little disagreement among the researchers? That life span is flexible
(有弹性的), but there is a limit, says George Martin of the University of Washington. "We can get flies to
live 50 percent longer," he says. "But a fly"s never going to live 150 years." Of course, if you became a new
species (物种), one that ages at a lower speed, that would be a different story, he adds.
Does Martin really believe that humans could evolve (进化) their way to longer life? "It"s pretty cool to
think about," he says with a smile.
B. Old people are creative.
C. Women are sporty at 85.
D. Women live longer than men.
enough to carry home. But you need to remember:
1.
Take a hammer with you for breaking open rocks (岩石). A hammer is the best kind to use. A pair of
glasses will stop flying pieces of stones from hurting your eyes.
2.
A hand lens is useful. You might find fossils that are too small to see clearly. With a hand lens you can
examine the small things better.
3.
Take a map of the area you"re visiting to show you where you might find the fossils, plus a ruler for
measuring(测量) the fossils you find.
4.
A camera will be useful for photographing interesting rocks which stand up out of the ground. That"ll
help you to remember where you found the fossils.
5.
Number your fossils and wrap (包、裹) them in newspapers before putting them into your bag.
6.
Make sure that your clothing is suitable for the weather in whatever kind of countryside you are visiting.
7.
You have to take a notebook and pencils. As soon as you find something interesting, take a note of
where you found it and the kind of rock in which it was found.
was one that is still very important today -the wheel. This made it easier to carry heavy things and to travel
a long distance.
For hundreds of years after that there were few inventions that had as much effect (作用) as the wheel.
Then in the early 1800"s the word started to change. There was little unknown land left in the world. People
didn"t have to explore much anymore. They began to work hard to make life better.
In the second half of the 19th century many great inventions were made. Among them were the camera,
the electric light and the radio. These all became a big part of our life today.
The first part of the 20th century saw more great inventions. The helicopter (直升飞机) in 1909. Sound
movies in 1926. The computer in 1928. And jet planes in 1930. This was also a time when a new material was
first made. Nylon came out in 1935. It changed the kind of clothes people wear.
The middle part of the 20th century brought new methods (方法) to help people get over diseases. They
worked very well. They made people healthier and let them live long lives. By the 1960"s more people could
expect to live to be at least 60.
By this time most people had a very good life. Of course new inventions continued to be made. But man
now had a wish to explore again. The world is known to man but the stars are not yet. Man began looking for
ways to go into space. Russia made the first step. Then the United States took a step. since then other countries,
including China and Japan, have made their steps into space.
In 1969 man took his biggest step away from earth. American first walked on the moon. This is certainly
just a beginning though. New inventions will someday allow us to do things we have never yet dreamed of.
How does reading this message make you feel? Why did the sender use all capital letters? Was he or she
angry, or did that person just forget to turn off the "Caps Lock" on the computer? The fact is, this e-mail
"sounds" like the writer is shouting because using all capital letters in an e-mail is usually the way that people
shout online.
Knowing when and when not to use capital letters is just one example of online etiquette (规矩) often
called netiquette. Virginia Shea"s book, Netiquette, lists a basic set of dos and don"ts for communicating
(交流) rightly with others online. Following are some of her suggestions.
First, always remember that you are sending messages to a real person, not just to a computer. Don"t
type anything that you wouldn"t say to someone"s face. Also, remember that the person who receives your
message cannot hear the tone of your voice, or see the expression on your face, so make sure your meaning
is clear.
Don"t do anything online that you wouldn"t do in real life. Don"t take anything without paying for it,
unless it"s free. Don"t use information that someone else has written, and say it"s yours. Don"t read other
people"s e-mail-you wouldn"t open your next-door neighbor"s mailbox and open their mail, right? Do share
your knowledge of the Internet with others. It"s a big place with lots of information, and there are many new
things to discover.
Remember that people think about you by your words as well as your actions, so do try to write well.
Good writing skills, as well as correct grammar and spelling, do matter. Send polite, well-written e-mail
messages to others. If you"re uncertain about how to spell a word or which phrase to use, look it up. There
are lots of helpful books and websites.
It"s okay to express your opinions online in forums like chat rooms or message boards, for example
"MSN" or "QQ", but don"t start arguments with people. "Flame wars" (网上论争) in online discussions can
be interesting to read, but are often unfair (不公平) to other members of the group. Express your ideas, but
remember that fighting (打架) on or offline is just not right.
When you"re online, just as in "real" life, try to respect other people"s space, privacy, and feelings.
Remember, you"re not the only one traveling on this highway!
or fight back. Plants certainly cannot run away, and they have no teeth and claws. But plants can defend (保护)
themselves by using both physical and chemical ways.
Some plants have their own ways to keep animals away. For example, the leaves of the holly (冬青) plant
have sharp prickles (刺) that stop grass-eating animals. Holly leaves on lower places have more prickles than
leaves on upper places. This is because the lower leaves are easier for most animals to reach.
Some plants, such as the oak tree (橡树), have thick and hard leaves that are difficult for animals to eat.
Some grasses may contain a sandy material, eating such grasses wears down the animal"s teeth.
Many plants also have chemical defenses. Some plants produce chemicals that taste bitter or cause an
unpleasant reaction. Some plants may fight against an attack by increasing the production of these chemicals.
When a worm (虫子) bites a tobacco leaf (烟叶), the leaf produces a chemical smell.
Many plants depend on both physical and chemical defenses. A certain plant in China, for instance, has
prickly leaves, and each prickle has poisonous water (毒液). Only one experience with this kind of plant will
teach an animals to stay away from it is the future.
1. Can plants move from place to place?
____________________________________________________________
2. Can plants defend themselves by physical ways or by chemical ways?
____________________________________________________________
3. Why lower holly leaves have more prickles than upper ones?
____________________________________________________________
4. How does tobacco defend itself against an attack from a worm?
____________________________________________________________
5. What kind of experience will teach an animal to stay away from a plant in the future?
____________________________________________________________
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