For many years, scientists couldn't figure out how atoms and molecules on the Earth combined to make living things. Plants, fish, dinosaurs, and people are made of atoms and molecules, but they are put together in a more complicated way than the molecules in the primitive ocean. What's more, living things have energy and can reproduce, while the chemicals on the Earth 4 billion years ago were lifeless.
After years of study, scientists figured out that living things, including human bodies, are basically made of amino acids and nucleotide bases. These are molecules with millions of hydrogen, carbon, nitrogen, and oxygen atoms. How could such complicated molecules have been formed in the primitive soup? Scientists were stumped.
Then, in 1953, two scientists named Harold Urey and Stanley L. Miller did a very simple experiment to find out what had happened on the Primitive Earth. They set up some tubes and bottles in a closed loop, and put in some of the same gases that were present in the atmosphere 4 billion years ago: water vapor, ammonia, carbon dioxide, methane, and hydrogen.
Then they shot an electric spark through the gases to simulate bolts of lightning on the ancient Earth, circulated the gases through some water, sent them back for more sparks, and so on. After seven days, the water that the gases had been bubbling through had turned brown. Some new chemicals were dissolved in it. When Miller and Urey analyzed the liquid, they found that it contained amino acids-the very kind of molecules found in all living things.
46. When did scientists come to realize how the atoms and molecules on the Earth combined to make living thing?
A. 4 billion years ago. B.1953. C. After seven days. D. Many years later.
47. Scientists figured out that human bodies are basically made of .
A. amino acids
B. molecules
C. hydrogen, carbon, nitrogen and oxygen atoms
D. water vapor, ammonia, carbon dioxide, methane and hydrogen
48. Harold Urey and Stanley L.Miller did their experiment in order to .
A. find out what had happened on the Earth 4 billion years ago
B. simulate bolts of lightning on the ancient Earth
C. dissolve some new chemicals
D. analyze a liquid
49. At the end of the last paragraph, the underlined word "it" refers to.
A. a closed loop B. an electric spark C. water D. the liquid
50. According to the writer, living things on the Earth include .
A. atoms and molecules B. chemicals
C. plants, fish, dinosaurs and human beings D. the primitive soup
If your mother wants to tell you something, she uses words. Birds can not talk as we do. But some birds can make sounds to warn their young of danger. They have their own ways to make the young birds do certain thing.
The jackdaw is a kind of blackbirds that lives in Europe. Jackdaws live together in flocks. ( 群) Yong jackdaws do not know their enemies. When an older jackdaw sees a dog , it makes a loud tattling (格格响的)sound.The young birds know this sound means an enemy is nearby. The sounds warns them to know their enemy.
If a young jackdaw is in a dangerous place, a jackdaw parent flies over him from behind.The parent bird flies low over the young bird’s back, the parents’ tail feathers move quickly from side to side, It is trying to say, “ Follow me.”
At the same time , the parent calls out, “ Key-aw ,Key-aw.” The parent means, “ Fly home with me.” The young bird then follows the older one home.
Young jackdaws do not have to learn what certain sounds mean.They know the meaning of these sounds from the time they hatch. The jackdaw lives in _____ .
| A．Europe | B．Australia | C．America | D．Africa |
When an old jackdaw sees a dog , it _____ .
| A．calls out “Follow me .” | B．makes a loud sound |
| C．flies away | D．fights the dog . |
Parent jackdaw can use their tail feathers to ______ .
| A．ask their young to follow them | B．play a game with the young |
| C．tell the meal time | D．give a warning of a fire |
The story tells much about _____ .
| A．the danger of jackdaws. |
| B．in which mother can talk to their children. |
| C．the way jackdaws warn their young of danger. |
| D．how the jackdaws are living. |
Which of the following does this story lead you to believe ?
| A．All animal parents can talk to their young. |
| B．Dogs are the most dangerous enemies for jackdaws. |
| C．Young jackdaws know the meaning of their parents’ sound when they grow older . |
| D．Some birds can give certain information to one another. |
Nothing was going right for Dr.Turner at the hospital. He made a mistake while operating on a patient. He felt sure he was no longer trusted and decided to change his job . One day he learned from the paper that a doctor was looking for a partner (合作者). The doc-tor, whose name was Johnson , lived in Thorby, a small town in the north of England.
A few days later Dr. Turner went to Thorby, and arrived at Dr.Johnson's home early in the afternoon. Though old and a little deaf, Dr.Johnson still had a good brain. He kept talking to the visitor about the town and its people. When they turned to the question of partnership,it was already seven in the evening. Dr. Johnson invited Dr . Turner to have dinner with him in a restaurant before catching the train back to London. Dr . Turner noticed that Dr. Johnson was fond of good food and expensive wines . They had an excellent meal. When the bill was brought, Dr. Johnson felt in his pocket." Oh, dear," he said. "I've forgotten my money." "That's all right,"Dr. Turner said."I'll pay the bill."As he did so,he began to wonder whether Dr. Johnson was worthy of trust. Dr. Turner decided to leave his present job because.
| A．he had never been trusted |
| B．it demanded too great skills |
| C．he believed it offered little hope for his future |
| D．he thought the hospital would like him to leave |
The two doctors spent most of the afternoon talking about.
| A．things of no interest to Dr. Johnson |
| B．things of no importance to Dr. Turner |
| C．health matters |
| D．food and drink |
The story suggests that.
| A．Dr. Johnson did notlike Dr. Turner |
| B．the two doctors would become friends |
| C．the two doctors would not work together |
| D．Dr. Turner decided to stay at his present job |
The words did so in the last sentence mean.
| A．caught the train back to London | B．felt in his pocket |
| C．paid the bill | D．said those words |
Santa Fe, the capital of New Mexico, U.S.A.,is in the central part of the state, on the Santa Fe River, which flows into the Rio Grande 35 kilometres west of the city. More than two thousand metres above sea level, it lies in the Sangre de Cristo Mountains with the Ortiz Mountains to the southeast.
Santa Fe was founded in 1609 by the Spanish (西班牙人)on an old Indian village.In 1680 the Indians seized the place but only held it for twelve years before the Spanish retook it. The city remained under Spanish rule until Mexico won its independence (独立) in 1821. From then on it was a Mexican city until 1846 when it was taken over by American troops.
With a population of 48,953, Santa Fe is now the second largest city in the state. Because of its sunny weather, rich history and surrounding mountains, it is a good place for holiday makers. Besides hunting and skating in the mountains people enjoy shopping in the Indian and Spanish shops, which brings a large income to the city every year. In summer there is an international opera (歌剧) season when operas are shown in a partly-roofed ,open-air theatre daily for people from all over the world.At present Santa Fe belongs to.
| A．India | B．Mexico | C．Spain(西班牙) | D．the United States |
Which of the drawings below gives an idea of what Santa Fe is like?
RG="the" Rio Grande SFR="the" Santa Fe River OM="the" Ortiz Mountains
Santa Fe was under the rule of the Mexicans in.
| A．1675 | B．1695 | C．1816 | D．1833 |
The people who held Santa Fe for the longest period in history were the .
| A．Spanish | B．Indians | C．Mexicans | D．Americans |
What is of special interest to people who visit Santa Fe in summer?
| A．Hunting. | B．Fishing. | C．Watching operas. | D．Doing shopping. |
Santa Fe is best described (描述) as a .
| A．trade centre | B．holiday centre | C．home for all nations | D．seaport city |
One of the reasons for visitors to come to Santa Fe is that it.
| A．has fine weather | B．is the state capital |
| C．has historical monuments | D．is on the Santa Fe River |
If English means endless new words, difficult grammar and sometimes strange pronunciation, you are wrong. Haven't you noticed that you have become smarter since you started to learn a language?
According to a new study by a British university, learning a second language can lead to an increase in your brain power. Researchers found that learning other languages changes grey matter. This is the area of the brain which processes information. It is similar to the way that exercise builds muscles.
The study also found the effect is greater, the younger people learn a second language.
A team led by Dr Andrea Mechelli, from University College London, took a group of Britons who only spoke English. They were compared with a group of "early bilinguals" who had learnt a second language before the age of five, as well as a number of later learners.
Scans showed that grey matter density (密度) in the brain was greater in bilinguals than in people without a second language. But the longer a person waited before mastering a new language, the smaller the difference.
"Our findings suggest that the structure of the brain is changed by the experience of learning a second language," said the scientists.
It means that the change itself increases the ability to learn.
Professor Dylan Vaughan Jones of the University of Wales, has researched the link between bilingualism and maths skills. "Having two languages gives you two windows on the world and makes the brain more flexible (灵活的),"he said. "You are actually going beyond language and have a better understanding of different ideas."
The findings were matched in a study of native Italian speakers who had learned English as a second language between the ages of two and 34. Reading, writing, and comprehension were all tested. The results showed that the younger they started to learn, the better. "Studying a language means you get an entrance to another world," explained the scientists.The main subject talked about in this passage is ______.
| A．science on learning a second language |
| B．man’s ability of learning a second language |
| C．1anguage can help brain power |
| D．1anguage learning and maths study |
In the second paragraph, the writer mentions “exercise” in order to ______.
| A．say language is also a kind of physical labor |
| B．prove that one needs more practice when he (she) is learning a language |
| C．to show the importance of using the language when you learn the language |
| D．make people believe language learning helps grey matter work well |
We may know from the scientific findings that ______.
| A．the earlier you start to learn a second language, the higher the grey matter density is |
| B．there is no difference between a later second language learner and one who doesn't know a second language |
| C．the experience of learning a second language has bad effect on people's brain |
| D．the ability of learning a second language is changing all the time |
The underlined word “bilingual'’ probably means ______.
| A．a researcher on language learning |
| B．a person who is good at learning foreign languages |
| C．a person who can speak two languages |
| D．an active language learner |
Who says Americans worship the almighty (全能的) dollar? It's not true. Having enough free time is more important to most Americans than being rich, according to a new survey.
Only 13 percent of more than 2,400 people questioned in the telephone survey ranked being wealthy as most important to them, while 67 percent ranked free time as their top priority (优先考虑的事), higher than having a successful career, getting married, and having children. "Everyone wants free time to do the things they want to do, young, middle-aged or old," said Richard Morin, of the Pew Social ~ Demographic Trends Project, which conducted the survey. "So our desire to play unites us."
The survey also showed that people who were educated in university valued career success over wealth, so did middle-aged people. Not surprisingly, those who didn't have money, ranked wealth very highly. This included minorities, first generation Americans and less educated people. The survey also revealed that a disproportionate (不成比例的) number of people under the age of 30 and retired people in the group made $ 20,000 or less a year. But the emphasis on wealth lessens with age, with younger people putting value on it but hardly any seniors. "It just diminishes (减弱) with time as the reality sets in that you would never be rich," Morin said. "But also, as for old people the reality sets in that you don't have to be rich to lead a very comfortable and fulfilling life. "
While wealth was not at the top of people's list of priorities, 43 percent still said it was somewhat important.The survey showed that the majority of American people ranked ______ as the most important.
| A．wealth | B．a successful career | C．marriage | D．free time |
Who cares least for wealth, according to the passage?
| A．Young people | B．First generation Americans |
| C．Old people | D．Less-educated people |
According to the survey, what did middle-aged people regard as more important?
| A．success in career | B．education level | C．wealth | D．comfort |
What is the belief of old people according to the third paragraph?
| A．Wealth is as important to the old as health. |
| B．One needs to put money away for his retired life. |
| C．One doesn't have to be rich to live a satisfying life. |
| D．One would never get rich until he retires. |