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[单选题]

Metals () when they are heated.

A.extend

B.enlarge

C.spread

D.expand

答案

D、expand

发布时间：2023-05-05

更多“Metals () when they are heated.”相关的问题

第1题

Several of the chemical elements were known in prehistoric【C1】______ . One of the great【C2

】______ forward in civilization came when bronze, an alloy,【C3】______ stone as the main material for tools and weapons. The iron replaced bronze. The first elements【C4】______ were those that were found free in nature or could be readily【C5】______ from their ores at relatively low temperatures. During the Middle Ages, chemistry was mostly practised by the alchemists,【C6】______ tried to turn base metals into gold, and who were interested in discovering a way of living for【C7】______ . But they discovered many important【C8】______ about the metals and some of the most easily attainable compounds. Even before the Middle Ages, people knew how to【C9】______ mercury, tin, and iron from their ores. By the time of Paracelsus, chemistry was developed largely to the effort of【C10】______ medicines.

【C1】

A．times

B．schedules

C．plans

D．timing

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第2题

RecyclingOne of the most important changes in how modern societies respond to the problems

Recycling

One of the most important changes in how modern societies respond to the problems of waste and its disposal is the development of techniques and processes for recycling materials that have been thrown away. Of course, recycling means that the material was cycled before. What the word really means is that the material has gone from a raw material to a factory or production process to use by a consumer. Most plastics, for example, began as crude oil from oil wells. A manufacturing process changes some of the chemicals in oil to plastics. The plastics are made into thousands of products and sent on to consumers who use them. When consumers are finished with their plastic bottles or toys or packages, they throw them away.

Unfortunately, as we often see on automobile bumper stickers, "Throw it away？ There is no away." What that means, of course, is that as we produce more and more waste, safe and easy places to put it are be coming fewer and fewer. Moreover, oil for plastics, trees for paper, and coal and oil to make heat for glass and metal production are also becoming harder to find and more expensive. One solution that can help solve problems of both supply and disposal is recycling, or using the same material more than once.

As an idea, recycling has been around for a long time. In fact, we might say that it has always been around, as long as people have used something after it has been used for something else. Using a coconut shell as a container after the coconut has been eaten may have occurred long ago. Glass jars are used to store screws or nails in many homes. Many industries have reused materials. Steel mills have added old steel to their furnaces, and glass companies have done the same with old glass. Paper has also been reused. In recent years, however, recycling is being seen as a more and more important way to reduce waste and the use of raw materials.

Many cities in the United States have begun recycling programs for household waste. Household waste, or the trash and garbage that we throw away from our homes, is made up mostly of paper. Food is the second largest part, but glass and metal are the next largest. Together, paper, glass, and metal make up almost 75 percent of the trash we throw away. If we could recycle much of that, we could greatly reduce the amount of trash we have to find a place for.

Some governments are also requiring more recycling. Japan already recycles about 50 percent of its household trash. The German government now has a very strict law requiring that most plastics and metal be recycled. This law has made a big change in the way automobiles are built and sold. Under the new law, automobile manufacturers must buy a car back when it is no longer useful. The car must then be separated into materials that can be recycled—metals, plastics, glass, and so on. This law has made automobile manufacturers think more carefully about the kinds of materials that go into automobiles and how those materials are used.

Recycling does not always go smoothly. Sometimes industries are not able to use all of the old material that is available.If paper manufacturers cannot use all of the old paper that is available, there will be no one to buy it and it will still have to be thrown away. The same is true for many metals and plastics. In Germany, problems have developed with their new law, because more materials are being recovered than manufacturers of new items can use. The government has to buy these materials, and it is costing a lot of money.

Closely related to the problem of usability is the problem of cost of recovery. There are many types of plastics, and not all of them can be reused or reused together. They have to be separated, cleaned, and sorted. Automobiles are made up of many types of metals and plastics. Separating all of these materials and recovering them for re

A．Y

B．N

C．NG

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第3题

听力原文：Few buildings on earth can compete with the legendary beauty of the Taj Mahal. To

听力原文： Few buildings on earth can compete with the legendary beauty of the Taj Mahal. Towering over the ancient Indian city of Agra, the Taj Mahal is the grandest monument to love ever created.

The lovers in this story are Ire 17th century Indian emperor Shah Jehan and his wife Mumtaz Mahal. She took a leading role in advising him, which is something unique for a woman to do for a husband who's an emperor. Over the course of their nineteen-year marriage she gave birth to 14 children. But in 1631 while trying to deliver their fifteenth -- she tragically died. He was heartbroken when she died. And after her death, he decided to build the world's greatest monument ever built, for love.

He ordered the royal architects to design the most beautiful building the world had known and decided to name it after his beloved, Mumtaz Mahal. He summoned twenty thousand laborers and sent wagons to all corners of his empire in search of precious metals and jewellery. And after seventeen years of construction, the monument was completed and his beloved empress was moved to her final resting place.

(33)

A．Because there are priceless treasures.

B．Because it is the most beautiful building.

C．Because it is the tomb for an empress.

D．Because it is the grandest monument to love ever created.

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第4题

Pollution occurs whenever unnatural substances are introduced into an environment. Most

ocean pollution caused by humans are concentrated along the 【M1】______ coasts of continents. Lets see what some of the pollutants are. Industrial wastes sometimes get to seawater. Often, 【M2】______ these contain(concentrations)of metals and chemicals that harm organisms. Solid wastes, such as plastic bags and fishing line left lying on the beaches, can entangle in animals. Medical waste such as needles, plastic 【M3】______ tubing, and bags are a threat to both humans and animals. Pesticides, which include herbicides(weed killers) and insecticides(insect killers), used in farming reaching the ocean as runoff. They become 【M4】______ concentrating in the tissues of marine organisms. 【M5】______ Crop fertilizers and human sewage create a different kind of problem. They fertilize the water. This causes some types of algae to produce very rapidly. 【M6】______ When these algae die, theyre decomposed by huge amount of bacteria. The problem is that the bacteria use 【M7】______ up much of the oxygen in the water during respiration. However, other organisms such as fish cant get the 【M8】______ oxygen they need, and they die. Oil spills also pollute the ocean. Youve heard in the news about major oil spills caused to tanker 【M9】______ collisions, and leaks at offshore oil wells. Another source of oil pollution is oil mixed with wastewater thats pumped out of ships. In addition to these resources, oil discarded from cars and industries is 【M10】______ sometimes dumped into streams. It, too, eventually reaches the ocean.

【M1】

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第5题

NO LONGER DIFFERS ISSUING A. GOOD MONEY （62)______FROM BAD MONEY B. MAKE A PROFIT IN COI

NO LONGER DIFFERS ISSUING A. GOOD MONEY (62)______FROM BAD MONEY

B. MAKE A PROFIT IN COINAGE BY (63)______COINS

C. SILVER COINS ARE (64)______IN CIRCULATION LESS THAN 40 YEARS AGO IN THE UNITED STATES, IT WAS COMMON TO CHANGE A ONE-DOLLAR BILL FOR A DOLLAR"S WORTH OF SILVER. THAT IS BECAUSE THE COINS WERE ACTUALLY MADE OF SILVER. BUT THOSE DAYS ARE GON

E. THERE IS NO SILVER IN TODAY" S COINS. WHEN THE PRICE OF THE PRECIOUS METAL RISES ABOVE ITS FACE VALUE AS MONEY, THE METAL WILL BECOME MORE VALUABLE IN OTHER USES. (65)______BECAUSE THE SILVER IN COINS IS WORTH MUCH MORE THAN THEIR FACE VALU

E. A SILVER FIRM COULD FIND THAT IT IS CHEAPER TO OBTAIN SILVER BY MELTING DOWN COINS THAN BY BUYING IT ON THE COMMODITY MARKETS. COINS TODAY ARE MADE OF AN ALLOY OF CHEAPER METALS. GRESHAM" S LAW, NAMED AFTER SIR THOMAS GRESHAM, ARGUES THAT "GOOD MONEY" IS DRIVEN OUT OF CIRCULATION BY "BAD MONEY" . (66)______BECAUSE IT HAS HIGHER COMMODITY VALU

E. GRESHAM LIVED IN THE 16TH CENTURY IN ENGLAND WHERE IT WAS COMMON FOR GOLD AND SILVER COINS TO BE DEBASE

D. GOVERNMENTS DID THIS BY MIXING CHEAPER METALS WITH GOLD AND SILVER. THE GOVERNMENTS COULD THUS (67)______THAT HAD LESS PRECIOUS METAL THAN THE FACE VALUE INDICATE

D. BECAUSE DIFFERENT MIXINGS OF COINS HAD DIFFERENT AMOUNTS OF GOLD AND SILVER, EVEN THOUGH THEY BORE THE SAME FACE VALUE, SOME COINS WERE WORTH MORE THAN OTHERS AS COMMODITIES. PEOPLE WHO DEALT WITH GOLD AND SILVER COULD EASILY SEE THE DIFFERENCE BETWEEN THE " GOOD" AND THE " BAD MONEY. GRESHAM OBSERVED THAT COINS WITH A HIGHER CONTENT OF GOLD AND SILVER WERE KEPT RATHER THAN BEING USED IN EXCHANGE, OR WERE MELTED DOWN FOR THEIR PRECIOUS METAL. IN THE MID-1960S WHEN THE U.S. ISSUED NEW COINS TO REPLACE SILVER COINS, GRESHAM" S LAW WENT RIGHT IN ACTIO

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第6题

In impact testing of metals, metals will experience ductile failures with much greater absorption of

energy below the critical temperature.

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第7题

听力原文： Good afternoon. My name is Mary Raffety. For the next eleven weeks, I will be yo

ur lab instructor. The lab experiences you will be having are designed to complement your work in Dr Kaplan's inorganic chemistry course. Today's experiment is purposely a short one; it will help you become familiar with the lab setup and equipment.

As your lab instructor, it is my duty to assist you in setting up your experiments and understanding your results. I will also grade your lab notebooks. But I have an even more basic responsibility: your physical safety. I will insist on proper precautions, such as wearing protective goggles at all times. I also expect you to use common sense: don't wear long scarves that might catch fire; don't smoke; don't taste unknown substances.

Let me reinforce this point with a story. Issac Newton, perhaps the greatest scientist of all ages, lived in a period when the toxic effects of chemicals were less understood than today. He routinely sniffed fumes, tasted chemicals, and used open containers for heating substances. In the early 1690s, he suffered through a period of insomnia, depression, and mental instability. Though his biographers linked this situation to problems in his personal life, researchers now think it was a consequence of his lab procedures; they found abnormally high concentrations of lead, mercury, and other heavy metals in preserved specimens of his hair.

Consequently, we must learn from the past and put safety first.

At what point in the semester does this talk take place？

A．At the beginning.

B．In the middle.

C．Near the end.

D．During the final exam.

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第8题

Almost all metals are good conductors, silver______ the best of all.A．isB．beingC．has beenD

Almost all metals are good conductors, silver______ the best of all.

A．is

B．being

C．has been

D．is to be

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第9题

Ferrous metals include iron and alloys ofat least 50% iron.

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第10题

Today anyone will accept money in exchange for goods and services. People use money to buy

food, furniture, books, bicycles and hundreds of other things they need or want. When they work, they usually get paid in money.

Most of the money today is made of metal or paper. But people used to use all kinds of things as money. One of the first kinds of money was shells. Shells were not the only things used as money. In Chinese history, cloth and knives were used. In the Philippine Islands, rice was used as money for a long tie. Elephant tusks, monkey tails, and salt were used as money in parts of Africa. Cattle were one of the earliest kinds of money. Other animals were used as money, too.

The first metal coins were made in China. They were round and had a square hole in the center. People strung them together and carried them from place to place. Different countries have used different metals and designs for their money. The first coins in England were made of tin. Sweden and Russia used copper to make their money, Later, countries began to make coins of gold and silver.

But even gold and silver were inconvenient if you had to buy something expensive. Again the Chinese thought of a way to improve money. They began to use paper money. The first paper money looked more like a note from one person to another than the paper money used today.

Money has had an interesting history from the days of shell money until today.

Which of the following is the best title for this article？

A．Countries and Their Money.

B．Kinds of Money.

C．Trade and Money.

D．The History of Money.

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