What does fizz (气泡) taste like? In Bubbly (多泡的)drinks such as sodas, tiny bubbles give the drink a lift--- and have a distinct taste, In a new study on mice, scientists have connected that fizzy-taste feeling to the ability to taste sourness, such as that of oranges or vinegar.
Scientists first thought the taste of bubbles came from the bubbles bursting on the tongue, but now ate starting to think differently. Charles Zuker, of Columbia University, and his team studied the nervous system of mice to understand how the tongue tastes carbon dioxide, which is the gas that makes up the bubbles.
Animals, including human beings, are able to detect different tastes by using taste buds(味蕾) which pick up tastes in the mouth, and then send them to the brain. In the experiment, different groups of mice were genetically engineered to be missing one of the senses involved in taste. “Genetically engineered” means the researchers were able to turn off the switches for certain senses by changing the genes responsible for taste. The mice in one group could not taste sweet; another, sour; the third, bitter, and the fourth, salt. When the scientists gave carbon dioxide to the mice, the nervous systems of all the mice responded to the gas, except those of the mice that could not taste sour.
This shows that the taste of the bubbles must be sour, and that by turning off the ability of the mice to taste sour, the scientists also turned off their ability to taste carbon dioxide. When they studied the cells that detect sourness, the researchers found a protein attached to the cells that is important to the process of tasting carbon dioxide. When carbon dioxide comes into contact with this protein, the protein knocks off particles called protons. These protons(质子), in turn, travel to the brain, which says ,” Hey! That’s a taste!”
It may seem like a lot of work to get from a can of soda to a taste, but the science of the senses is anything but simple, “  Taste is a challenging system to study,” one researcher says.
【小题1】 What is the most important function of the bubbles?

A．Nervous Systems Understand How the Tongue Tastes.

B．The Process of Taste

C．The taste of Bubbles.

D．Different Animals Detect Different Tastes.

America, has always had people of many different nationalities and languages. The 1990 census (人口普查) indicates that almost 14% of Americans speak a non-English language at home. Yet only 3% reported that they spoke English “not well” or “not at all ”. That means that slightly more than one out of 10 Americans could be considered bilingual. Besides that, many high school and college students---and even some elementary school students---are required to take a foreign language. Actually, a growing number of Americans are coming to appreciate the benefits of using different languages.
Ethnic enclaves (少数民族聚居地) have preserved the language and culture of American immigrants. Some local residents can function quite well in their native language, without having to bother learning English. Regions such as southern Florida and the Southwest have numerous Spanish-speaking neighborhoods. In fact, Spanish speakers---numbering over 17 million---form the largest non-English linguistic group in America. But Chinese, Vietnamese, Italian, Polish and many other ethnic group add to the linguistic flavor of America. Foreign languages are so commonly used in some ethnic neighborhoods that visitors might think they are in another country!
Although some Americans welcome this linguistic and cultural diversity, others have begun to fear that the English language is being threatened. Since the 1980s, the “English Only ” movement has sought to promote legislation (立法) which would establish English as the “official language” and restrict the use of non-English language. However, some groups, including TESOL, the organization for Teachers of English to Speakers of Other language, object to such “language restrictionism”. But so far, 19 states have passed “English Only” legislation, and the topic is the focus of an ongoing debate.
Whether or not English is the official language of the United States, it remains the “language of wider communication”. Nearly everyone recognizes the need to develop the ability in using English in order to do well in America. American also recognize that English is the international language, and people with good English skills can get by in many international settings. On the other hand, in a world growing increasingly smaller, second language skills can be a great favor. They can build cross-cultural bridges and give people an edge in a variety of career field. Indeed, lack of foreign language skill can limit one’s chances for advancement and keep one in a cultural dead-end street. 
【小题1】 Ethnic groups have preserved their native languages because ______.

Burning the midnight oil before an exam or interview has an opposite effect according to a research which found that sleep is necessary for memories to be “downloaded” into the brain.

“A good night's sleep within 30 hours of trying to remember a new task is a necessary condition of having good recall in the weeks ahead，” scientists have found.

“We think that getting that first night's sleep starts the process of memory consolidation(加强)，” said Robert Stickgold, a sleep researcher at Harvard Medical School who conducted the latest study.

“It seems that memories are normally washed out of the brain unless some process nails them down. I feel uncertain that sleep is one of those things that do the nailing down，” Professor Stickgold said.

Professor Stickgold's team trained the 24 people to tell the direction of three diagonal bars (斜线) shown for a sixtieth of a second on a computer screen full of horizontal stripes(水平线)．

Half the subjects were kept awake that night, while the others slept. Both groups were allowed to sleep for the second and third nights to make up for any differences in tiredness between the volunteers.

Those who slept the first night were much better at remembering the task while the second group showed no improvement in spite of enjoying two nights of catch－up sleep.

A further study by scientists at the Medical University at Lubeck in Germany showed that memories are laid down in two stages during the night. The first is during the deep, so－called “slow wave” sleep, which usually takes place in the first half of the night. The second, and less important stage happens during the periods of dreaming or “rapid eye movement (REM)”. When people don't sleep well in the first half of the night, their memory consolidation is almost the same as having no sleep at all.

1. Which of the following statements is CORRECT according to the first paragraph?

A. It is necessary to burn the midnight oil before an exam or interview.

B. Sleep speeds up the loss of memory.

C. Man should have a good sleep if he wants to keep a good memory.

D. Staying up late will make you better prepared for an exam or interview.

2. It can be inferred from the fourth paragraph that________.

A. some process helps memories to be washed out of the brain

B. Professor Stickgold is doubtful about whether sleep can make memories worse

C. some memories normally influence the function of the brain

D. sleep may can improve the condition of memories

3. How was the research conducted by Professor Stickgold?

A. The subjects were divided into two groups.

B. All the subjects were kept awake for 3 nights.

C. One group slept at the first night but was kept awake the next two nights.

D. One group was kept awake for 3 nights but the other slept for the second and third nights.

4. What was the study result of the scientists' at the Medical University at Lubeck?

A. REM sleep is not important at all for the consolidation for memory.

B. Intellectual performance mainly depends on the slow wave sleep period.

C. When people sleep poorly in the first half of the night, it is almost the same as having no sleep at all.

D. REM sleep is as important as slow wave sleep in terms of memory recall.

5. The BEST title of this passage is “________”．

A. Sleep Necessary for Memories

B. The Importance of the First Stage of Sleep

C. Studies Made by Scientists About Sleep

D. The Scientists' Achievement in Sleep Research