Even if  you are a good high-jumper, you can jump only about seven feet off the ground. You cannot jump any higher because the earth pulls you hard. The pull of the earth is called gravity.

   You can easily find out the pull of the earth. If you weigh yourself, you will know how much gravity is pulling you. 来源：

   Since there is gravity, water runs down hill. When you throw a ball into the air, it falls back down. Because of gravity, you do not fall off the earth as it whirls (旋转) around. 来源：

   Then, can we get away from the earth and go far out into space? Now you can do it, because spaceships have been invented. Then spaceship will go so fast that it can escape (逃出) the earth’s gravity and carry you into space. 来源：

In this passage, the word “gravity” means_______.来源：

   A. the pull of everything.           B. the force of attraction(吸引) among objects.

   C. the force which attracts objects towards the centre of the earth来源：

   D. the force which attracts the earth towards the sun.

When you slip(滑) you always fall to the ground because________来源：

   A. the earth always turns round.                   B. the earth has gravity

   C. the earth’s gravity is greater than your weight.     D. you are careless. 来源：

Gravity is strong that_______

   A. it can throw a ball into the air.           B. it makes you jump only seven feet.

   C. it can let you fly away from the earth.     D. it can keep everything on earth.

Because of gravity,________

   A. water flows everything.            B. we can go everywhere by ship. 来源：

   C. water always flows downwards.     D. fish can live in water.

We can get away from the earth by spaceship because________

   A. the spaceship goes very fast.       B. the earth can’t pull the spaceship.

C. the spaceship has a strong force.    D. the spaceship can jump higher than others.

D
As they migrate（迁移），butterflies and moths choose the winds they want to fly with，and they change their body positions if they start floating in the wrong direction．This new finding suggests that insects may employ some of the same methods that birds use for traveling long distances．Scientists have long thought that insects were simply at the mercy of the wind．
Fascinating as their skills of flight are，migrating behavior has been difficult to study in insects because many long distant trips happthousands of feet above ground．Only recently have scientists developed technologies that can detect such little creatures at such great heights．
To their surprise，though，the insects weren’t passive travelers on the winds．In autumn，for example，most light winds blew from the east，but the insects somehow sought out ones that carried them south and they positioned themselves to navigate directly to their wintering homes．
Even in the spring，when most winds flowed northward，the insects didn’t always go with the flow．If breezes weren’t blowing in the exact direction they wanted to go，the insects changed their body positions to compensate．Many migrating birds do the same thing．
The study also found，butterflies and moths actively flew within the air streams that pushed them along．By adding flight speeds to wind speeds，the scientists calculated that butterflies and moths can travel as fast as 100 kilometers an hour．The findings may have real-world applications．With climate warming，migrating insects are growing in number．Knowing how and when these pests move could help when farmers decide when to spray their crops．
71．What’s the main idea of the text?
A．Insects migrate with the seasons．     B．Wind helps insects greatly in migrating．
C．Windsurfing insects have real direction．D．Scientists have trouble in observing insects．
72．Scientists originally thought that____________．
A．insects always waited for their favourable winds
B．insects chose the winds they wanted to ride
C．insects were just blown about by the wind
D．insects positioned themselves in the winds
73．It is not easy to stuay the migrating behavior of the insects because____________
A．the little creatures can fly very fast     B．they have no regular migrating courses
C．the wind’s direction is hard to foresee    D．their flight is long and high above ground
74．We can learn from the text that______________.
A．insects fly in the way birds do
B．insects travel more easily in autumn
C．insects never position themselves when flying low
D．insects rest a lot when the wind pushes them along
75．According to the passage，the findings can              ．
A．increase insects in number         B．instruct farmers when to spray
C．prevent climate warming       D．help protect insects

Even if we have an extremely healthy diet and lifestyle, the human body is programmed to wear out at a maximum of about 120 years, and usually less. We all have a biological clock inside us which determines the moment when our organs cease to function properly. This is because our cells have stopped renewing themselves and our body can no longer repair itself. This is also the moment when we are more likely to begin to suffer from the diseases of old age such as arthritis and Alzheimer’s. However, rapid advances in DNA research are beginning to throw light on the secrets of the ageing process. By the end of this century we could literally have the power of life over death.
Although it has long been accepted that humans have a fixed lifespan, it is also a fact that certain other organisms, such as reptiles and amphibians, appear to live indefinitely. The only reason we do not see 500-year-old alligators is because in the wild their lives are always in danger, from man, from pollution and from other animals. When they are kept in zoos they do not seem to age at all after they are fully grown. The same is true of some species of fish, which grow indefinitely and show no signs of ageing. The existence of animals with no fixed lifespan seems to indicate that an age gene really does exist. It is this gene which scientists are searching for, which may delay or repair damage to the body caused by ageing.
Another new area of research involves the oxidation（氧化） theory, which says that ageing is caused by the same process that makes iron rust. In controlled experiments, the lifespans of certain animals were shown to be lengthened with anti-oxidants; for example, the lifespan of mice can be increased by 30%. Antioxidants are already being used in face creams and other cosmetics, and they are likely to play an important part in keeping people physically young.
Perhaps the most immediate advance we are likely to see in the battle to halt（停止）the ageing process will be organ replacement. By the year 2020 it is likely that we will be replacing injured bones or even organs like livers and kidneys with ones “grown” in laboratories. By 2050 perhaps every organ in the body, except the brain, will have become commercially available. Recent experiments also show that it may one day be possible to “grow” new organs inside our body to replace worn-out ones, something which lizards and alligators already do.
Suddenly immortality（不死，不朽） seems within reach. We can begin to imagine a future where we are born, we grow to maturity, but we never grow old and die. But do we really want to live forever?
【小题1】 When all humans reach a certain age,         .

Even if he is not the most liked comedian in China today, his popularity certainly has risen the fastest within the last two months.
He's "Little Shenyang", who came into national fame overnight after his appearance on CCTV's Spring Festival Gala. With his funny cross-dressing, unique northeastern accent and superb imitative(模仿的) skills, Little Shenyang has obvious talent to support his rise to fame.
Hundreds of video clips of his shows have been posted on YouTube and other online video sites, and his performance fees reportedly grew 50-fold in just a few weeks. He has, at the same time, become one of the most controversial of entertainers.
Many have doubted his artistic potential, pointing out that his shows were repetitive and lacked creativity, a key to continued comedic success. Others belittle (轻视) the style of humor, saying it's too crude and appeals only to less-educated people. His defenders were just as up in arms. Many media commentators and bloggers said that his quick rise to star proved the broad appeal of his art form. He became a national champion not because of his "northeastern hick(乡巴佬)" humor, they argued, but because he represented something new on TV, something with a grassroots feel that appealed to millions of ordinary people.
Now, does Little Shenyang really deserve his star status?
【小题1】 Some people belittle Little Shenyang’s humor because _________. 

Even if he is not the most liked comedian in China today, his popularity certainly has risen the fastest within the last two months.

He's "Little Shenyang", who came into national fame overnight after his appearance on CCTV's Spring Festival Gala. With his funny cross-dressing, unique northeastern accent and superb imitative(模仿的) skills, Little Shenyang has obvious talent to support his rise to fame.

Hundreds of video clips of his shows have been posted on YouTube and other online video sites, and his performance fees reportedly grew 50-fold in just a few weeks. He has, at the same time, become one of the most controversial of entertainers.

Many have doubted his artistic potential, pointing out that his shows were repetitive and lacked creativity, a key to continued comedic success. Others belittle (轻视) the style of humor, saying it's too crude and appeals only to less-educated people. His defenders were just as up in arms. Many media commentators and bloggers said that his quick rise to star proved the broad appeal of his art form. He became a national champion not because of his "northeastern hick(乡巴佬)" humor, they argued, but because he represented something new on TV, something with a grassroots feel that appealed to millions of ordinary people.

Now, does Little Shenyang really deserve his star status?

1. Some people belittle Little Shenyang’s humor because _________. 

A. He represents something with a grassroots feel.

B. The style of humor lacked creativity.

C. He speaks with a northeast accent.

D. He became famous overnight.

2.What’s the secret of Little Shenyang’s success?                 

A. His funny cross-dressing.

B. His unique accent

C. His super imitative skills

D. All of the above

3.From the passage, we can infer that _________.                

A. Little Shenyang is the most popular comedian in China.

B. Few people like Little Shenyang’s performance.

C. Little Shenyang earns a lot of money now.

D. The author thinks little of Little Shenyang.