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).

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 many 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.

1.What does the underlined word “it” refer to?

A.Physical vitality.   B.Stress.           C.Aging.           D.Physical resistance.

2.Which of the following is not a change of aging?

A.People gradually lose their muscle strength.

B.Bones tend to break more easily.

C.The heart loses power and pumps less blood.

D.The lungs become unable to take in oxygen.zxxk

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

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

A.By keeping their physical fitness.          B.By cutting the calories in their diet.

C.By resetting their clock of aging.           D.By limiting the protein in their diet.

5.What is probably the best title for the article?

A.Two Great Experiments

B.The Mystery of Human Life

C.The Breakthrough in the Study of Aging

D.Ways to lengthen Human Life

 

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项

Health is the most important thing in the world. Nothing is more important than health. If we take away our money, houses, cars or even our clothes, we can still survive.   71   That is why we always try to eat in a healthy way and exercise regularly.

How can we keep healthy?In order to eat healthily, I usually avoid eating food high in fat, like French fries or cookies, which are junk foods.   72   I eat a lot of vegetables and fresh fruit which are full of vitamins.

   73   Taking exercise every day helps us build a strong body. Regular exercise is an important part of keeping me healthy.

What’s more, I think friends are an important part of one’s health.   74   I always feel better when I am with friends than when I am alone. When I am with my friends, I always laugh. Laughing is also an important part of health. It is good to stay with my friends.

By eating properly and exercising regularly, I can keep my body at a proper weight and keep healthy. By spending time with my friends, I can keep my mind as well as my body happy. These things sound easy to do, but not many people can manage them.    75  

A.On the other hand, doing exercise is very important.

B.There are some people who like staying alone, but they keep healthy.

C.Many studies show that people with a range of social contacts don’t get sick.

D.But if our health was taken away, it is certain that we would surely die.

E.I only eat little meat.

F.I think a strong will is necessary if we want to keep healthy.

G.Some people appear fat because they often eat too much.

 

As I understand, if scientists produced a human clone, there would be a great risk of it having a disease. Nobody seems to understand the ageing process of a clone. It would be terrible if a baby was the age of its parent at     31   . Its cells would grow old fast and it would die young.    32    until the technique is perfectly safe, it should be     33   .

I'd love to have a clone of     34   . I often wish I had a twin sister, someone who    35   me in everything. So why not a clone? Well, the idea    36   be fun but I'm not sure if it would be     37   . I think we would be playing with fire if we let scientists go ahead with     38   cloning. There are so many     39   

involved that all research in this area should be strictly controlled.

There are so many arguments     40    cloning that it is difficult to get anyone to consider the possible benefits. I am     41    that it is a technique which could be beneficial. The most obvious use would be for childless     42   . They would be able to have babies with their own genetic material. I don't see what's wrong with that.

Imagine a child     43    up knowing that his or her mother is really a sister or a brother. The emotional     44    on the child would be     45   . Or a child who was cloned from a dead brother or sister. What kind of emotional pressure would they feel, knowing they were made as a replacement for another? The whole idea

    46    me!

It's all very good to ban human cloning but scientists should be allowed to   47   

research. If they don't, we may     48    important benefits for our society, such as producing body organs. A clone is an     49    copy of a person with the same gene. Therefore, it is the     50    donor for an organ(器官) transplant.

1.

A.home

B.lab

C.process

D.birth

 

2.

A.Besides

B.Therefore

C.Although

D.Unless

 

3.

A.banned

B.allowed

C.encouraged

D.forced

 

4.

A.itself

B.herself

C.myself

D.yourself

 

5.

A.overlooked

B.contradicted

C.accumulated

D.resembled

 

6.

A.may

B.must

C.can

D.shall

 

7.

A.messy

B.safe

C.swift

D.awkward

 

8.

A.human

B.animal

C.plant

D.pet

 

9.

A.obligations

B.regulations

C.formulas

D.risks

 

10.

A.against

B.with

C.for

D.amid

 

11.

A.vanished

B.convinced

C.violated

D.teased

 

12.

A.couples

B.heroines

C.dwarves

D.elves

 

13.

A.picking

B.looking

C.getting

D.growing

 

14.

A.pressure

B.sample

C.privilege

D.ambition

 

15.

A.unsinkable

B.unimaginable

C.unbearable

D.unthinkable

 

16.

A.scratches

B.terrifies

C.entices

D.confronts

 

17.

A.continue

B.predict

C.tear

D.mention

 

18.

A.chase

B.contrast

C.cure

D.miss

 

19.

A.handy

B.identical

C.contradictory

D.transparent

 

20.

A.ideal

B.voluntary

C.vacant

D.inquisitive

 

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