Many people think of the brain as a mystery.They don't know much about intelligence and how it works.When they do think about what intelligence is，many people believe that a person is born smart，average，or dumb—and stays that way in the whole life.But new research shows that the brain is more like a muscle—it changes and gets stronger when you use it.And scientists have been able to show just how the brain grows and gets stronger when you learn.

Everyone knows that when you lift weights，your muscles get bigger and you get stronger.A person who can't lift 20 pounds when he/she starts exercising can get strong enough to lift 100 pounds after working out for a long time.That's because the muscles become larger and stronger with exercise.And when you stop exercising，the muscles shrink and you get weaker.That's why people say “Use it or lose it！”

But most people don't know that when they practice and learn new things，parts of their brain change and get larger a lot like muscles do when they exercise. Inside the cortex(皮层)of the brain are billions of tiny nerve cells，called neurons. The nerve cells have branches connecting them to other cells in a complicated network. Communication between these brain cells is what allows us to think and solve problems. When you learn new things，these tiny connections in the brain actually multiply and get stronger.The more you challenge your mind to learn，the more your brain cells grow.Then，things that you once found very hard or even impossible to do—like speaking a foreign language or doing algebra(代数)—seem to become easy after learning them for a period of time.The result is a stronger，smarter brain.

Scientists started thinking that the human brain could develop and change when they studied animals'brains.They found out that animals that lived in a challenging environment were more perspicacious—they were better at solving problems and learning new things.

1.According to the first paragraph，________.

A．the function of our brain is like that of the muscle

B．until now it's impossible to explain the brain's mystery

C．many people believe one's intelligence is naturally determined

D．one's brain grows stronger as the age increases

2.Training muscles is compared to ________.

A．using the brain

B．connecting things in your brain

C．lifting weights

D．doing research about the brain

3.What does the underlined word“perspicacious”in the last paragraph probably mean?

A．Strong.? ????????????? B．Smart.

C．Popular.? ????????????? D．Active.

4.The following paragraph will most probably talk about ________.

A．the differences between animals'brains and humans'brains

B．the relation between human brains and muscles

C．scientists' findings about animals' brains

D．how to make your brain smarter through self?development

As you dash outdoors in the middle of winter, you might make it halfway down the block before realizing that your ears are freezing because you forgot your hat.

Now, scientists have shown that even though you’ve had an apparent memory lapse（丧失）, your brain never forgot what you should have done.

Memory works mainly by association. For example, as you try to remember where you left your keys, you might recall you last had them in the living room, which reminds you that there was an ad for soap on television, which reminds you that you need soap, and so on. And then, as you’re heading out of the door to buy soap, you remember that your keys are on the kitchen counter. Your brain knew where the keys were all along. It just took a round-about way to get there.

Now, scientists at the Salk Institute for Biological Studies are studying associative memory in monkeys to figure out just how this complicated process works.

First, the researchers trained a group of monkeys to remember arbitrary（任意的） pairs of symbols. The researchers showed the monkeys one symbol（cold weather） and then gave them the choice of two other symbols, one of which （a hat） would be associated with the first. A correct choice would earn them a sip of their favorite juice.

Most of the monkeys performed the test perfectly, but one kept making mistakes.

“We wondered what happened in the brain when the monkey made the wrong choice, although it apparently learned the right pairing of symbols,” said study leader Thomas Albright.

Albright and his team observed signals from the nerve cells in the monkey’s inferior temporal cortex （ITC）, an area of its brain used for visual pattern recognition and for storing this type of memory.

As the monkey was deciding which symbol to choose, about a quarter of the activity in the ITC was due to the choice behavior.

Meanwhile, more than half the activity was in a different group of nerve cells, which scientists believe represent the monkey’s memory of the correct symbol pairing, and surprisingly, these cells continued to work well even when the monkey chose the wrong symbol.

“In this sense, the cells ‘knew’ more than the monkeys let on in their behavior,” Albright said. “Thus, behavior may vary, but knowledge endures.”

What is the main idea of this passage?

A. Your brain remembers what you forget.

B. Activity is a round-about way to memory.  

C. Monkeys have better memory than us.

D. Your brain may forget something, but not always.

The example of the keys and soap is given to explain the relationship between _______.

A. memory and our daily life   B. memory and television ads

C. memory and association       D. memory lapse and human brain

The researchers believe the monkey that made the wrong choice ________.

A. had some trouble with its nerve system  B. failed to see the objects well

C. had the worst memory     D. also knew the correct answer

The underlined word “endures” may be best replaced by __________.

A. increases        B. remains      C. disappears       D. improves

People who have lost the ability to understand or use words due to brain damage are called aphasics(失语症患者). Such patients can be extremely good at something else. From the changing expressions on speakers’ faces and the tones of their voices, they can tell lies from truths.

Doctors studying the human brain have given a number of examples of this amazing power of aphasics. Some have even compared this power to that of a dog with an ability to find out the drugs hidden in the baggage.

Recently, scientists carried out tests to see if all that was said about aphasics was true. They studied a mixed group of people. Some were normal; others were aphasics. It was proved that the aphasics were far ahead of the normal people in recognizing false speeches — in most cases, the normal people were fooled by words, but the aphasics were not.

Some years ago, Dr. Oliver Sacks wrote in his book about his experiences with aphasics. He mentioned a particular case in a hospital. Some aphasics were watching the president giving a speech on TV. Since the president had been an actor earlier, making a good speech was no problem for him. He was trying to put his feelings into every word of his speech.

But his way of speaking had the opposite effect on the patients. They didn’t seem to believe him. Instead, they burst into laughter. The aphasics knew that the president did not mean a word of what he was saying. He was lying!

Many doctors see aphasics as people who are not completely normal because they lack the ability to understand words. However, according to Dr. Sacks, they are more gifted than normal people. Normal people may get carried away by words. Aphasics seem to understand human expressions better, though they cannot understand words.

1.What is so surprising about aphasics?

2. How did the scientists study aphasics?

3.What do we learn from this text?

　 As we know, Human beings each have unique brains. The brain is of the greatest importance to the body. It is the boss of the body．Your eyes，ears，nose，and skin tell your brain what is going on around you．Other parts of your body tell your brain what is going on inside of you．Your brain takes in the signals．It tells your body what to do with them．When you touch fire，your skin tells your brain that your finger is too hot．Your brain tells you to move your finger．All these happen very fast．Your brain also controls your breathing，blinking，and heartbeat．It controls your feelings and thoughts too．
　　Humans have the most developed brain of all animals．Yet it is not the largest brain．The human brain weighs three pounds．The brain of an elephant weighs 11 pounds．So the largest brain is not always the best brain．In people，a larger brain does not mean a clever person．
【小题1】What is the main idea of this passage?
　 

A single night of taking the drug Ecstasy (摇头丸) can cause serious brain damage and speed up the start of Parkinson’s disease, scientists say. Just two or three Ecstasy tablets can permanently destroy brain cells that affect movement and reasoning, according to American research that links the drug to Parkinson’s for the first time.
A study by a team at Johns Hopkins University in Baltimore, Maryland, involving squirrel monkeys and baboons (狒狒) found that both species suffered permanent damage to key cells, which are lost in Parkinson’s, after receiving three low doses（剂量）of Ecstasy at three-hour periods.
The study is particularly important because baboons are one of the best animal models for the human brain. George Ricaurte, who led the research, said that the widespread abuse of drug might have caused severe damage. “The most troubling result is that young adults using Ecstasy may be increasing their risk of developing Parkinsonism as they get older.”
Alan Leshner, a former director of the US National Institute on Drug Abuse, said, “This study emphasizes the multi-aspect damage that Ecstasy causes to users. We’ve long known that repeated use damages brain cells. But this study shows that even very occasional use can have long-lasting effects on many different brain systems. It sends an important message to young people: don’t experiment with your own brain.”
Janet Betts, a mother whose teenage daughter Leah died after a single Ecstasy tablet in 1995, said, “This comes as no surprise. But people can’t see the effects at first, and they say it won’t happen to them. We’ll see the symptoms later, just as we have with smoking.”
【小题1】 The article is intended to ______.

A．Because their brain is similar to human being’s.

B．Because these animals usually take drugs.

C．Because these animals will soon get well after the experiment.

D．Because there is a model in the animals’ brains.

A．Leah died after a single Ecstasy tablet in 1995

B．taking drug has the same symptoms as smoking

C．occasional use of the drug can have long-lasting effects on the brain systems

D．people have long known that repeated use of the drug damages brain cells