B
When people lose legs after accidents or illnesses, emergency care and artificial limbs（假肢）often allow them to walk again. Newts （蝾螈） in the same situation, on the other hand, can grow limbs back on their own! Scientists have known for a long time that certain animals can re-grow limbs, but they haven’t quite figured out how these creatures do it.
Researchers have now come up with some new ideas. Their work may give people the ability to re-grow lost limbs. The researchers started with two simple experiments：when you cut a newt’s leg at the ankle, only the foot grows back；when you cut off a leg at the very end, the whole leg grows back. In both cases, the re-growth begins with stem cells. Stem cells can develop into nearly any type of cell in the body.
How do a newt’s stem cells know when to grow only a foot and when to re-grow a whole leg?
This question relates to another mystery. In newt’s, a cut-off leg will grow back only if the nerve bundle（神经束）in it also grows back , but if something prevents the nerve bundle from growing, the stem cells at the wound won’t re-grow a new leg.
In its study, a British team focused on a protein called n-AG. When the team prevented nerves in a limb from growing, but added the n-AG protein to stem cells in the limb, the limb still re-grew. That protein seems to guide limb re-growth. People have proteins that are similar to n-AG. Further research into these materials may someday help human limbs recover by themselves.
40. In the experiments, the researchers cut off a newt’s foot or leg to find out _____.
A. what stem cells were                     B. whether they would grow back
C. how long it would take to re-grow    D. how they would re-grow
41. A newt will re-grow its leg if _____.
A. its ankle was cut off but the nerve bundle was good
B. its leg was cut off and the nerve bundle stopped growing
C. its leg was cut off and the nerve bundle could grow back
D. its ankle and the nerve bundle were cut off
42. What do the underlined words “these materials” refer to?
A. Nerve bundles and proteins.         B. Proteins similar to n-AG.
C. Stem cells and proteins.               D. Stem cells and nerve bundles.
43. The first sentence of the passage _____.
A. acts as a lead–in                       B. shows where researchers got their new ideas
C. states the author’s opinion           D. describes the result of researchers’ studies

Here is some news of the future.

March 20, 2035

There was a lot of news around the life extension drugs that hit the market a decade ago. They didn't promise that you would like forever, but they gave you a chance to extend your life an extra five to ten years. Even though the life expectancy rate at birth has increased greatly, the life expectancy for seniors hasn't improved that much. Basically, you have a greater chance to become a senior, but you will not have a much longer lifespan, and this is where the anti-aging drugs intend to kick in. So, do the anti-aging drugs work? Well，it is too early to tell. But the sales so far are very good.

April 19, 2035

Of the total US population of 378 million, people over 65 years of age now make up 20% for the first time. The senior ratio of only 4.1% by year 1900, and 12.4% 30 years ago.

The number of people above 65 compared to those of what is considered working ages, between 15 and 64, is currently 33.7%. This is up from 18.5% since year 2005, which means that for every retired person there are now two workers, compared to four workers 30 years ago. The number of people above the age of 80 has grown to 23.8 million, making them 6.3% of the total population compared to 3.6% in 2005.

April 12, 2040

Although introduced in the market only five years ago, 10% of all hydrogen fuel now sold in the US is of the environmentally friendly Re-Hydro label, produced through eletrolysis(电解) based on a source of 100% renewable energy. Several producers have turned to producing Re-Hydro, mainly because of lower tax, which also keeps the price of Re-Hydro on the same level as regular hydrogen. Most analysts believe that Re-Hydro will be the dominating fuel in the future.

1.According to News 1 we know that the life extension drugs ____.

A．were first sold in the year 2025.

B．are made to make people live forever.

C．should be taken when people are young.

D．have greatly increased the life expectancy rate at birth.

2.The sales of the life extension drugs so far clearly show that_____.

A．people have no faith in them

B．people want to give them a try

C．they work very well for seniors

D．they have no effect on people’s health

3.What can we learn from News 2?

A．Many Americans will find it hard to find a job.

B．It’s very hard for seniors to pass the age of 80.

C．The US population has been increasing rapidly since 2005.

D．The US population has been aging rapidly since 2005.

4.We can know from the passage that the fuel of the Re-Hydro label is ______.

A．expensive         B．cheap            C．green            D．dangerous

5.What can we infer from News 3?

A．Re-Hydro will be widely used in the future.

B．The government discourages the production of Re-Hydro.

C．Producers are not interested in producing Re-Hydro.

D．Re-Hydro is more expensive than regular hydrogen.

Grown-ups know that people and objects are solid. At the movies, we know that if we reach out to touch Tom Cruise, all we will feel is air. But does a baby have this understanding?
To see whether babies know objects are solid. T. Bower designed a method for projecting an optical illusion(视觉影像)of a hanging ball. His plan was to first give babies a real ball, one they could be expected to show surprised in their faces and movements, All the 16 to 24-week-old babies tested were surprised when they reached for the illusion and found that the ball was not there.
Grown-ups also have a sense of object permanence. We know that if we put a box in a room and lock the door, the box will still be there when we come back. But does a baby realize that a ball that rolls under a chair does not disappear and go to never-never land?
Experiments done by Bower suggest that babies develop a sense of object permanence when they are about 18 weeks old. In his experiments, Bower used a toy train that went behind a screen. When 16-week-old and 22-week-old babies watched the toy train disappear behind the left side of the screen, they looked to the right, expecting it to re-appear. If the experiment took the train off the table and lifted the screen, all the babies seemed surprised not to see the train. This seems to show that all the babies had a sense of object permanence. But the second part of the experiment showed that this was not really the case. The re-searcher substituted(替换) a ball for the train when it went behind the screen. The 22-week-old babies seemed surprised and looked back to the left side for the train. But the 16-week-old babies did not seem to notice the switch(更换).Thus,the 16-week-old babies seemed to have a sense of “something permanence,” while the 22-week-old babies had a sense of object permanence related to a particular object.
【小题1】The passage is mainly about        .

Going Zero Waste means more than just managing the rubbish we create．It means reducing it too．While it might seem like a difficult thing to do, it's well worth it．And what better time to start than Christmas?

We need to copy the way Nature wastes nothing．Many things are created by human society that we know will soon become useless and be thrown out．How many plastic bottles or even PCs end up in the rubbish bin? Instead，we should design products that can be more easily repaired，reused and recycled．

Kamikatsu, a Japanese village，has already gone Zero Waste．The 2，000 villagers compost their leftovers，and recycle everything else．There are 34 different boxes at the re-cycling centre! Residents grumble about the inconvenience，but they also see the benefits．

People who live Zero Waste lives are careful about what they do．They never take more than they need．Reusing plastic bags at supermarkets is a great way to reduce waste．And those who plan before they shop avoid having to throw food out later．Also，it’s best not to go food shopping when you’re hungry：You’ll be sure to buy too much!

Let’s think about how to enjoy a Zero Waste Christmas．By sending recyclable cards，we can help our friends and family reduce waste．And what better way to enjoy the spirit of Christmas than with a real tree that can be replanted in the spring?

Going Zero Waste requires us to think more about what happens before and after we act．It takes ambition，and it's not always easy．But just think how good it would be，both for ourselves and for the environment, if we never had to waste anything．

1.When is this passage probably written?

2.What should we do to reduce waste according to the passage?

3.If we want to live Zero Waste lives we should do the following except        .

4.What’s the main purpose of this passage?

Grown-ups know that people and objects are solid. At the movies, we know that if we reach out to touch Tom Cruise, all we will feel is air. But does a baby have this understanding?

To see whether babies know objects are solid. T. Bower designed a method for projecting an optical illusion(视觉影像)of a hanging ball. His plan was to first give babies a real ball, one they could be expected to show surprised in their faces and movements, All the 16 to 24-week-old babies tested were surprised when they reached for the illusion and found that the ball was not there.

Grown-ups also have a sense of object permanence. We know that if we put a box in a room and lock the door, the box will still be there when we come back. But does a baby realize that a ball that rolls under a chair does not disappear and go to never-never land?

Experiments done by Bower suggest that babies develop a sense of object permanence when they are about 18 weeks old. In his experiments, Bower used a toy train that went behind a screen. When 16-week-old and 22-week-old babies watched the toy train disappear behind the left side of the screen, they looked to the right, expecting it to re-appear. If the experiment took the train off the table and lifted the screen, all the babies seemed surprised not to see the train. This seems to show that all the babies had a sense of object permanence. But the second part of the experiment showed that this was not really the case. The re-searcher substituted(替换) a ball for the train when it went behind the screen. The 22-week-old babies seemed surprised and looked back to the left side for the train. But the 16-week-old babies did not seem to notice the switch(更换).Thus,the 16-week-old babies seemed to have a sense of “something permanence,” while the 22-week-old babies had a sense of object permanence related to a particular object.

1.The passage is mainly about        .

A.babies’sense of sight                   B.effects of experiments on babies

C.babies’understanding of objects          D.different tests on babies’feelings

2..In Paragraph 3, “object permanence” means that when out of sight, and object           .

A.still exists        B.keeps its shape           C.still stays solid      D.is beyond reach

3..What did Bower use in his experiments?

A.A chair         B.A screen              C.A film            D.A box

4.. Which of the following statements is TRUE?

A.The babies didn’t have a sense of direction.

B.The older babies preferred toy trains to balls.

C. The younger babies liked looking for missing objects

D.The babies couldn’t tell a ball from its optical illusion.