_______,the runners crossed the finish line.

Like distance runners on a measured course, all of us will move through time in a roughly predictable pattern.
In the first stage of our lives, we develop and grow, reaching toward the top of physical vitality (活力,生气).
After we grow up, however, the body begins a process of gradually wearing out.
A new awareness of physical fitness may help lengthen our years of health and vitality, yet nothing we do will work to stop the unavoidable force of aging.
Most of the changes of aging take place deep inside the body. The lungs become less able to take in oxygen. Powerful muscles gradually lose their strength. The heart loses power and pumps less blood. Bones grow easier to break.
Finally, we meet a stress, a stress that is greater than our physical resistance. Often, it is only a minor accident or chance infection (a disease caused by virus), but this time, it brings life to an end.
In 1932, a classic experiment nearly doubled the lifetime of rats, simply by cutting back the calories in their diet. The reason for the effect was then unknown.
Today, at the University of California at Berkley, Dr. Paul Seagle has also greatly lengthened the normal lifetime of rats. The result was achieved through a special protein limited diet, which had a great effect on the chemistry of the brain. Seagle showed that within the brain, specific chemicals control many of the signals that influence aging. By changing that chemical balance, the clock of aging can be reset.
For the first time, the mystery of why we age is being seriously challenged. Scientists in ma ny fields are now making striking and far-reaching discoveries.
An average lifetime lasts 75 years, yet in each of us lies a potential for a longer life. If we could keep the vitality and resistance to disease that we have at age twenty, we would live for 800 years.
小题1: What does the underlined word “it” refer to?

A．Physical vitality.

B．Stress.

C．Aging.

D．Physical resistance.

小题2:Which of the following is not a change of aging?

A．The lungs become unable to take in oxygen.

B．People gradually lose their muscle strength.

C．The heart loses power and pumps less blood.

D．Bones tend to break more easily.

小题3: The author believes the following except that ________.

A．human’s life pattern is predictable

B．physical fitness can’t stop the force of aging

C．human’s lifetime will last longer than 75 years

D．all of the changes of aging take place deep inside the body

小题4:How did Dr. Paul Seagle lengthen the lifetime of rats in his experiment?

A．By limiting the protein in their diet.	B．By cutting the calories in their diet.
C．By resetting their clock of aging.	D．By keeping their physical fitness.

小题5: What is probably the best title for the article?

A．Two Great Experiments	B．The Mystery of Human Life
C．Ways to lengthen Human Life	D．The Breakthrough in the Study of Aging

Liu Xiang is regarded ____ one of the best runners in the world.

A．as

B．like

C．for

D．with

[ ]

Runners in a relay race pass a stick in one direction. However, merchants passed silk, gold, fruit, and glass along the Silk Road in more than one direction. They earned their living by traveling the famous Silk Road.
The Silk Road was not a simple trading network. It passed through thousands of cities and towns. It started from eastern China, across Central Asia and the Middle East, and ended in the Mediterranean Sea. It was used from about 200 BC to about 1300 AD, when sea travel offered new routes. It was sometimes called the world’s longest highway.
However, the Silk Road was made up of many routes, not one smooth path. They passed through what are now 18 countries. The routes crossed mountains and deserts and had many dangers of hot sun, deep snow and even battles. Only experienced traders could return safe.
The Silk Road got its name from its most prized product. Silk could be used like money to pay taxes or buy goods. But the traders carried more than just silk. Gold, silver, and glass from Europe were much found in the Middle East and Asia. Horses traded from other areas changed farming practices in China. Indian merchants traded salt and other valuable goods. Chinese merchants traded paper, which produced an immediate effect on the West. Apples traveled from central Asia to Rome. The Chinese had learned to graft (嫁接) different trees together to make new kinds of fruit.
They passed this science on to others, including the Romans. The Romans used grafting to grow the apple. Trading along the Silk Road led to world-wide business 2,000 years before the World Wide Web.
The people along the Silk Road did not share just goods. They also shared their beliefs. The Silk Road provided pathways for learning, diplomacy, and religion.
小题1:It’s probable that traders along the Silk Road needed ______.

A．to deal with a lot of difficulties	B．to know the making of products
C．to receive certain special training	D．to remember the entire trade route

小题2:The Silk Road became less important because ______.

A．it was made up of different routes	B．silk trading became less popular
C．people needed fewer foreign goods	D．sea travel provided easier routes

小题3:New technologies could travel along the Silk Road because people ______.

A．shared each other’s beliefs	B．learned from one another
C．traded goods along the route	D．earned their living by traveling

小题4:What is the best title for the passage?

A．The Silk Road: Past and Present	B．The Silk Road: East Meets West
C．The Silk Road: Routes Full of Dangers	D．The Silk Road: Pathways for Learning

Experience the Colorado River the Hualapai Way! River Runners Offers the ONLY One Day White-water Trip ANYWHERE at the GRAND CANYON! Since 1973, Hualapai River Runners has been conducting white-water rafting journeys on the Colorado River. Our experienced guides expertly sail along the river and share the history of the Canyon and the Hualapai people with you. Visitors experience the excitement of whitewater rapids and then stop to enjoy the impressive beauty of Travertine Falls and a tasty lunch. No charge for children 2 years and under. One-Day Trip Retail $249.00 + $79.00 (helicopter and round-trip ground transportation) White-water rafting tours begin in Peach Springs. Hualapai River Runners transports you to Diamond Creek, which is the starting point for the 37 mile rafting tour. Lunch is included and upon arrival at the rafting tour termination point (终点), fly out of the Grand Canyon by helicopter to Grand Canyon West. Two-Day Trip Retail $549.00 + $79.00 (helicopter and round-trip ground transportation) Two-day rafting trips with one night on the Colorado River. All supplies and meals are included. Two days in the Grand Canyon, on the Colorado River, allows more time to explore one of the Seven Wonders of the World. Tours Include: • Round-trip transportation from Peach Springs to the starting point and from the termination points back to Peach Springs. • Snack, drinks and lunch (vegetarian meals available upon request). • Waterproof dry bags for storing your cameras, sunscreen, dry clothes, etc. The helicopter part of transportation is weather permitting. If the helicopter transportation is cancelled because of bad weather, the raft will continue an additional two hours to South Cove and a maximum $20.00 per customer will be given back. Special website booking rate 15% off rafting in June 2011. So book now! Call us Toll Free Today! Tel: 1-888-868-9378

小题1:Where do white-water rafting tours start?

A．Travertine Falls.	B．The Grand Canyon.
C．Grand Canyon West.	D．Diamond Creek.

小题2:Which of the following is TRUE about the trip?

A．Hualapai River Runners provides dry clothes.

B．You will get $20 back if you are not satisfied.

C．The trip is free of charge for children under 2.

D．Online booking has a better offer all year round.

小题3:It can be learned from the text that _________.

A．the guides can help you learn sailing

B．the cost includes snack, drinks and lunch

C．the helicopter transportation can save you three hours’ time

D．the Grand Canyon is well-known for its history

小题4:What is the purpose of the text?

A．To explain how to make a rafting trip.

B．To explore the Hualapai culture.

C．To attract people to the sights.

D．To introduce the history of the Colorado River