Most people know precious gemstones (宝石) by their appearances. An emerald flashes deep green, a ruby seems to hold a red fire inside, and a diamond shines like a star. It’s more difficult to tell where the gem was mined, since a diamond from Australia or Arkansas may appear the same to one from the Democratic Republic of the Congo. However, recently, a team of scientists has found a way to identify a gemstone’s origin.
Beneath the surface of a gemstone, on the tiny level of atoms and molecules, lie clues to its origin. At this year’s meeting of the Geological Society of America in Minneapolis, Catherine McManus reported on a technique that uses lasers to clarify these clues and identify a stone’s homeland. McManus directs scientific research at Materialytics, in Killeen, Texas. The company is developing the technique. “With enough data, we could identify which country, which mining place, even the individual mine a gemstone comes from,” McManus told Science News.
Some gemstones, including many diamonds, come from war-torn countries. Sales of those “blood minerals” may encourage violent civil wars where innocent people are injured or killed. In an effort to reduce the trade in blood minerals, the U.S. government passed law in July 2010 that requires companies that sell gemstones to determine the origins of their stones.
To figure out where gemstones come from, McManus and her team focus a powerful laser on a small sample of the gemstone. The technique is called laser-induced breakdown spectroscopy. Just as heat can turn ice into water or water into steam, energy from the laser changes the state of matter of the stone. The laser changes a miniscule part of the gemstone into plasma, a gas state of matter in which tiny particles called electrons separate from atoms.
The plasma, which is superhot, produces a light pattern. (The science of analyzing this kind of light pattern is called spectroscopy.) Different elements produce different patterns, but McManus and her team say that gemstones from the same area produce similar patterns. Materialytics has already collected patterns from thousands of gemstones, including more than 200 from diamonds. They can compare the light pattern from an unknown gemstone to patterns they do know and look for a match. The light pattern acts like a signature, telling the researchers the origin of the gemstone.
In a small test, the laser technique correctly identified the origins of 95 out of every 100 diamonds. For gemstones like emeralds and rubies, the technique proved successful for 98 out of every 100 stones. The scientists need to collect and analyze more samples, including those from war-torn countries, before the tool is ready for commercial use.
Scientists like Barbara Dutrow, a mineralogist from Louisiana State University in Baton Rouge, find the technique exciting. “This is a basic new tool that could provide a better fingerprint of a material from a particular locality,” she told Science News. We learn from Paragraph 1 that __________________.
| A．an emerald and a ruby are names of diamonds. |
| B．it’s not difficult to tell where the gem was mined. |
| C．appearances help to identify the origin of gemstones. |
| D．diamonds from different places may appear the same. |
Why did the U.S. government pass law that requires companies selling gemstones to determine the origins of their stones?
| A．To look for more gemstones. |
| B．To encourage violent civil wars. |
| C．To reduce the trade in blood minerals. |
| D．To develop the economy. |
Which of the following facts most probably helps McManus and her team in identifying the origin of stones?
| A．Heat can turn ice into water or water into steam. |
| B．Gemstones from the same area produce similar light patterns. |
| C．Laser can changes a miniscule part of the gemstone into plasma. |
| D．Materialytics has already collected patterns from thousands of gemstones. |
From the last two paragraphs, what can be inferred about the laser technique?
| A．It is ready for commercial use. |
| B．People can use the new tool to find more gemstones. |
| C．It can significantly reduce the gemstones trade in blood minerals. |
| D．It will bring about a revolutionary change in identifying the origin of minerals. |
The author wrote this passage mainly to ________.
| A．tell us how to identify the origin of diamonds. |
| B．introduce a laser technique in identifying a stone’s origin |
| C．prove identifying the origin of gemstones are difficult |
| D．attract our attention to reducing trade in blood minerals |
There are some very good things about open education .This way of teaching allows students to grow as people ,and to develop their own interests in many subjects .Open education allows students to be responsible for （负责）their own education, as they are responsible for what they do in life .Some students do badly in traditional classrooms. The open classroom may allow them to enjoy learning .Some students will be happier inan open education school . They will not have to worry about grades or rules .For students who worry about these things a lot, it is a good idea to be in an open classroom.
But many students will not do well in an open classroom. For some students ，there are too few rules .These students will do little in school. They will not make good use of open education. Because open education is so different from traditional education, these students may have a problem of getting used to making so many choices. For many students it is important to have some rules in the classroom. They worry about the rules even when there are no rules .Even a few rules will help this kind of students. The last point about open education is that some traditional teachers do not like it .Many teachers do not believe in open education. Teachers who want to have an open classroom may have many problems at their school.
You now know what open education is .Some of its good points and bad points have been explained .You may have your own opinion about open education. The writer thinks that open education is a good idea, but only in theory. In actual fact, it may not work very well in a real class or school. The writer believes that most students, but of course not all students, want some structure in their classes. They want and need to have rules. In some cases, they must be made to study some subjects .Many students are pleased to find subjects they have to study interesting. They would not study those subjects if they did not have to.Open education allows students to .
| A．grow as they are educated |
| B．be responsible for their future |
| C．develop their own interests |
| D．discover subjects outside class |
Some students like open education but some students will do little in an open classroom because.
| A．there are too few rules |
| B．they hate activities |
| C．open education is similar to traditional education |
| D．they worry about the rules |
Which of the following is Not mentioned in the passage?
| A．Some traditional teachers do not like open education. |
| B．Many teachers do not believe in open education. |
| C．Teachers may have problems in open classroom. |
| D．The teachers’ feelings and attitudes are important to the students. |
Which of the following can best summarize（总结）the passage?
| A．Open education is a really complicated idea. |
| B．Open education is better than traditional education. |
| C．Teachers dislike open education. |
| D．Open education is a good idea in practice. |
Going to the beach is many American’s favorite activity. They went swimming in the ocean without giving a thought to what was underwater. But those days are long gone. In the summer of 1988, many of the beaches had to be closed because garbage（废料）from hospitals was found in the water. The garbage included glass bottles with samples of blood, and people were afraid they might get AIDS from the blood. At some beaches, sewage（下水道）was found in the water. Americans were shocked by this state of affairs. People didn’t think of the underwater garbage because it was out of sight.
Some of the most polluted waters still look beautiful. San Francisco Bay is a good example of a beautiful bay that’s full of chemicals. Scientists discovered pollution in some lakes and rivers when they found fish with rotting skin. People are told not to eat too much fish because of pollution. Most American cities put their garbage in the ground. But New York and a few other cities put their garbage in the ocean. Boston Harbor is so polluted that scientists say it won’t recover until the next century. The government has ordered the city to build a sewage treatment plant, Cleaning up oceans won’t be easy, but people can no longer ignore（忽视）this challenge.The main idea of the article is that _____.
| A．ocean waters around America have become polluted. |
| B．Americans are bringing too much garbage to the beach. |
| C．beaches were closed because Americans were shocked. |
| D．going to the beach is many American’s favorite activity. |
The oceans are polluted by _____.
| A．swimmers, AIDS patients and fish. |
| B．Boston, San Francisco and New York only. |
| C．garbage, sewage and medical waste and so on. |
| D．swimmers and fishes |
Many polluted waters are beautiful because _____.
| A．chemicals can be beautiful. |
| B．they have been cleaned up. |
| C．pollution is underwater or hard to see. |
| D．there are still many fish in them |
More people can go to the beaches near Boston if _____.
| A．the city puts its garbage in the ground |
| B．a sewage plant is built |
| C．they don’t eat too much fish |
| D．they stop polluting the water |
A man once said how useless it was to put advertisements in the newspapers, “Last week,” said he, “my umbrella was stolen from a London church. As it was a present, I spent twice its worth in advertising, but didn't get it back.”
“How did you write your advertisement?” asked one of the listeners, a merchant.
“Here it is,” said the man, taking out of his pocket a slip cut from a newspaper. The man took it and read, “Lost from the City Church last Sunday evening, a black silk umbrella. The gentleman who finds it will receive ten shillings on leaving it at No. 10 Broad Street.”
“Now,” said the merchant, “I often advertise, and find that it pays me well. But the way in which an advertisement is expressed is often very importance. Let us try for your umbrella again. and if it fails, I'll buy you a new one.”
The merchant then took a slip of paper out of his pocket and wrote: “If the man who was seen to take an umbrella from the City Church last Sunday evening doesn't wish to get into trouble, he will return the umbrella to No. 10 Broad Street. He is well known.”
This appeared in the paper, and on the following morning, the man was astonished when he opened the front door. In the doorway lay at least twelve umbrellas of all sizes and colors that had been thrown in, and his own was among the number. Many of them had notes fastened to them saying that they had been taken by mistake and begging the loser not to say anything about the matter.The result of the first advertisement was that ______.
| A．the man got his umbrella back |
B．the man wasted some money advertising |
| C．nobody found the missing umbrella | |
| D．the umbrella was found somewhere near the Church |
“If it fails, I’ll buy you a new one .” suggested that____.
| A．he was quite sure of success |
| B．he was not sure whether he would get the umbrella hack |
| C．he was rich enough to afford a new umbrella |
| D．he did not know what to do |
This is a story about _____.
| A．a useless advertisement |
| B．how to make an effective(有效) advertisement |
| C．how the man lost and found his umbrella |
| D．what the merchant did for the umbrella owner |
A car needs gas to run and your body also needs food to work for you. Eating the right kind of food is very important. It can help your body grow strong to take care of what you eat.
There are four main food groups altogether. The dairy group has food like milk, cheese and sour milk（酸奶）. The other three groups are the meat and fish group, the fruit and vegetable group, and the bread and rice group. Each meal should have at least one food from all four main groups. With all these food together, you will be given enough energy during the day.
It is easy to get into bad eating habits. You may eat your breakfast in a hurry to get to school on time. Or you may not have time for a good lunch. It may seem easy to finish your supper with fish and chips all the time. But you will find yourself tired in these days and you can not think quickly.
Watching what you eat will help keep your body healthy and strong. It is also good to take some exercise. It will help you eat more if you take a walk or play games in the open air. Having a good eating habit with some exercise is the key to your health.Which of the following is a good eating habit?
| A．Going to school without any breakfast |
| B．Eating fish and chips for supper all the time.. |
| C．Having at least one food from all four groups each meal. |
| D．Having different food from all four food groups. |
In this passage the writer mainly tells us that _____.
| A．every person needs food to grow well |
| B．taking exercise can keep your body strong |
| C．the right kind of food with exercise will keep you healthy |
| D．enough energy helps people think more quickly |
The underlined word “dairy” in the second passage means _____.
| A．the food made out of cows such as milk and butter |
| B．she shop that sells milk and butter |
| C．a farm where cows are kept |
| D．a place where milk products are made. |
The best title for this passage is _____.
| A．The Four Food Groups | B．A Healthy Diet |
| C．Your Body And Food | D．Food And Your Health |
After Christmas, I took a job in the clothes department at Graham’s for the first fortnight of the January sale. I can’t say that I enjoyed it, but it was an experience I’ll never forget.
I could never understand why there were so many things in the sales. Now I know the secret! Firstly, there is the special winter stock and the stock that people buy all the year round. Some of these things are slightly reduced. Secondly, there are the summer clothes they couldn’t sell last year; these are heavily reduced to clear them. Thirdly, there are cheap clothes bought in especially for the sales; these are put out at high prices ten days before the sale begins and then are reduced by 60% in the sale. Lastly, they buy in “seconds” for the sale and they are sold very cheaply.
When I arrived half an hour before opening on the first day of the sale, there was already a queue around three sides of the building.
When the big moment arrived to open the doors, the security guards, looking less confident than usual, came up to them, keys in hand. The moment they had unlocked the doors, they hid behind the doors for protection as the noisy crowd charged in. I couldn’t believe my eyes; this wasn’t shopping. It was a battlefield! One poor lady couldn’t keep her feet and was knocked over by people pushing from behind.
Clothes were flying in all directions as people searched for the sizes, colors and styles they wanted. Quarrels broke out. Mothers were using their small children to crawl through people’s legs and get hold of things they couldn’t get near themselves.
Within minutes I had half a dozen people pushing clothes under my nose, each wanting to be the first served. Where had the famous English queue gone? The whole day continued like that, but I kept my temper! I was taking money hand over fist and began to realize why, twice a year, Graham’s were happy to turn their expensive store into a battlefield like this.
In the sale fever, people were spending money like water without thinking if they needed what they were buying. As long as it was a bargain, it was OK.
You won’t believe this, but as soon as I got home, I crashed out for four hours. Then I had dinner and went back to bed, fearing the sound of the alarm which would tell me to get ready for the second day of the sale.What kind of clothes is likely to be sold only a little cheaper according to the passage?
| A．Last summer’s clothes. | B．Clothes not in perfect condition. |
| C．Clothes bought in specially for the sales. | D．Clothes for winter. |
Which of the following statements is TRUE according to the passage?
| A．The customers gave up the queuing as soon as the sale began. |
| B．The customers kept their temper while looking for clothes they wanted. |
| C．Small children were not helpful to their mothers in the sale. |
| D．The security guards of the clothes department were as confident as usual. |