The ability to conduct electricity is one of the key properties of a metal. Other solid material such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost electrons. This leaves the metal atoms with a positive charge and they are now strictly ions. The lost electrons are free to move in what are known as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.

An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the 'lead' of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow.

Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor or electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.

According to the passage, a metal can conduct electricity due to________.

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Scientists have developed a new bionic computer chip that can be mated with human cells to combat disease. The tiny device, smaller and thinner than a strand of hair, combines a healthy human cell with an electronic circuitry chip. Doctors can control the activity of the cell by controlling the chip with a computer.
It has long been established that cell members become permeable when exposed to electrical impulses. Researchers have conducted genetic research for years with a trial-and-error process of bombarding cells with electricity in an attempt to introduce foreign substances such as new drug treatments or genetic material. They were unable to apply a particular level of voltage for a particular purpose. With the new invention, the computer sends electrical impulses to the chip, which triggers the physicians to open a cell‘s pores with control.
Researchers hope that eventually they will be able to develop more advanced chips whereby they can choose a particular voltage to activate particular tissues, whether they be muscle, bone, brain, or others. They believe that they will be able to implant multiple chips into a person to deal with one problem or more than one problem.

The author implies that up to now. the point of applying electric impulse to cells was to     .

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It/ considered/ most/ popular/ sporting event/ the world.

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Nobody ……….. to stay home on such a lovely summer day.

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Mary jogs everyday ______ lose weight.

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Television has transformed politics in the United States by changing the way in which information is disseminated, by altering political campaigns, and by changing citizen's patterns of response to politics. By giving citizens independent access to the candidates, television diminished the role of the political party in the selection of the major party candidates. By centering politics on the person of the candidates, television accelerated the citizen's focus on character rather than issues. Television has altered the forms of political communication as well. The messages on which most of US reply are briefer than they once were. The stump speech, a political speech given by travelling politicians and lasting 1/2 to 2 hours, which characterized nineteenth-century political discourse, has given way to the 30-second advertisement and the 10 second "sound bite" in broadcast news. Increasingly the audience for speeches is not that standing in front of the politician but rather the viewing audience tvho will hear and see a snippet of the speech on the news. In these abbreviated forms, much of what constituted the traditional political discourse of earlier ages has been lost. In 15 or 30 seconds, a peaker cannot establish the historical context that shaped the issue in question, cannot detail the probable causes of the problem, and cannot examine alternative proposals to argue that one is preferable to others. In snippets, politicians assert but do not argue. Because television is an intimate medium, speaking through it require a changed political style that was more conversational, personal, and visual than that of the old-style stump speech. Reliance on television means that increasingly our political world contains memorable pictures rather than memorable words. Schools teach US to analyze words and print. However, in a word in which politics is increasingly visual, informed citizenship requires a new set of skills. Recognizing the power of television's pictures, politicians craft televisual, staged events, called pseudo-event, designed to attract media coverage. Much of the political activity we see on television news has been crafted by politicians, their speechwriters, and their public relations advisers for televised consumption. Sound bites in news and answers to questions in debates increasingly sound like advertisements.
1. What is the main point of the passage?

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Any change in one part of an ecosystem can cause changes in other parts. Droughts, storms and fires can change ecosystems. Some changes (1) _______ ecosystems. If there is too (2) _______ rainfall, plants will not have enough water to live. If a kind of plant dies off, the animals that feed on it may also die or move away. Some changes are good for ecosystems. Some pine forests need fires for he pine trees to reproduce. The seeds are sealed inside pinecones. Heat from a forest fire melts the seal and lets the seeds (3) _______. Polluting the air, soil, and water can harm ecosystems. Building (4) _______ on rivers for electric power and irrigation can harm ecosystems around the rivers. Bulldozing wetlands and cutting down forests destroy ecosystems. Ecologists are working with companies and governments to find better ways of (5) _______ fish, cutting down trees, and building dams. They are looking for ways to get food, lumber, and other products for people without causing harm to ecosystems

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The ____________ will announce tomorrow’s weather on TV at 7:30 tonight.

Read the reading below carefully, and then complete it with the best option A, B, C or D given below:
The World Health Organization (WHO) is a (1) ____________ agency of the United Nations that is concerned with international public health. It was established on 7 April 1948, and is headquartered in Geneva, Switzerland. The WHO is a member of the United Nations Development Group. Its predecessor, the Health Organization, was an agency of the League of Nations. The WHO constitution was signed (2) ____________ 61 countries (all 51 member countries and 10 others) on 22 July 1946, with the first meeting of the World Health Assembly (3) _____________ on 24 July 1948. It incorporated L'Office International d'Hygiène Publique and the League of Nations Health Organization. Since its establishment, it has played a leading role in the (4) ______________ of smallpox. Its current priorities include communicable diseases, in particular HIV/AIDS, Ebola, malaria and tuberculosis; the mitigation of the effects of non-communicable diseases such as sexual and reproductive health, development, and aging; nutrition, food security and healthy eating; occupational health; substance abuse; and driving the development of reporting, publications, and networking. The WHO is responsible for the World Health Report, the worldwide World Health Survey, and World Health Day. The current Director-General of the WHO, Tedros Adhanom, also served as Ethiopian Health Minister from 2005 to 2012 and as Ethiopian Foreign Minister from 2012 to 2016. Adhanom started his five-year (5) ___________ on 1 July 2017

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By the age of 25, he ............two famous novels.

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Scientists have developed a new bionic computer chip that can be mated with human cells to combat disease. The tiny device, smaller and thinner than a strand of hair, combines a healthy human cell with an electronic circuitry chip. Doctors can control the activity of the cell by controlling the chip with a computer.
It has long been established that cell members become permeable when exposed to electrical impulses. Researchers have conducted genetic research for years with a trial-and-error process of bombarding cells with electricity in an attempt to introduce foreign substances such as new drug treatments or genetic material. They were unable to apply a particular level of voltage for a particular purpose. With the new invention, the computer sends electrical impulses to the chip, which triggers the physicians to open a cell‘s pores with control.
Researchers hope that eventually they will be able to develop more advanced chips whereby they can choose a particular voltage to activate particular tissues, whether they be muscle, bone, brain, or others. They believe that they will be able to implant multiple chips into a person to deal with one problem or more than one problem.

The word “strand" in the second sentence is closest in meaning to     .

Read the passage below carefully, and then choose the best answer:
Incredible Shrinking Microchips
There is a popular old saying that “bigger is better”. Although this may be true in some regards, the exact opposite often applies in technology. As electronic components get smaller, it allows companies to manufacture tinier devices with more features. Thus began the never-ending quest to create the smallest microchips on the planet. Yet as these vital electronic components get smaller, they are also getting stronger and clever inventors are finding new ways in which to use them to do incredible things. Currently, the biggest limitation microchip producers face when trying to reduce chips’ size is the copper wires that provide electrical current throughout the chip. Although they can be made smaller, this can cause a whole host of problems such as melting and overheating. Thanks to the work of a few scientists from the UK though, this problem may soon be a thing of the past. Their solution is getting rid of the copper wiring altogether and using carbon nanotubes instead. Not only would this allow for smaller sizes but it would also increase the power that microchips can generate. In the end, this would translate into smaller and more powerful devices much to the delight of consumers all over the world. Corporate powerhouse Intel® has announced plans to create a line of tiny, low power chips that can be used in bracelets, smart watches, and other tiny devices. The chips will be called Intel® Quark, and they are being designed primarily to fit in biomedical devices. A key selling point to biomedical technology is that the devices have to be nonintrusive because people don’t want to carry around heavy equipment to monitor their health. If they can do this, Intel® will likely find several tablet and smartphone manufacturers who are willing to corporate Quark microchips into their devices. In a somewhat unusual project, researchers are working on a special microchip that will serve as miniature human organs in experiments. These “organ” chips could be used to test different medicines and study diseases. If realized, the technology could put an end to the use of lab mice and other animals for testing. Everyone from the largest pharmaceutical companies to the US military has shown interest in the project. Currently, the research team in charge of the project believes that within five years the organ chips will be used in practical research. It goes to show that thinking small often produces the biggest results.
2. The word “this” in paragraph 2 refers to ________.

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word for each of the blanks.
Owning a car has several advantages. .......................(1), you can go wherever you want, whenever you want. You  don’t  have  to  depend  on  public  transport,  and ................ (2), you will feel more independent.
 ..................(3), you are able to give lifts to friends, or carry heavy loads of shopping. ....................(4), there can be certain financial problems, especially if you live in a city. Running a car can be costly, since you have to spend quite an amount on items................... (5) petrol, servicing the car, and repairs. You might also have problem with parking, as every where is more and more crowded with cars. ............ (6) most people feel that the advantages of owning a car outweigh the disadvantages.

(3)................. 

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:
The American type of football was developed in the 19th century from soccer and rugby football. Played by professionals, amateurs, college and high school students, or young children, football in American is one of the most popular sports besides basketball and baseball. It attracts millions of fans each fall and people are very supportive of their favourite teams. The football playing field of today is rectangular in shape and measures 100 yards long and 53.5 yards wide. White lines are painted on the playing field to mark off the distances to the end zone. The games is divided into four quarters, each fifteen minutes long. The first two quarters are known as the first half. There is a rest period between two halves which usually last about fifteen minutes. Each team has eleven players. Each team has offensive players who play when the team has possession of the ball and defensive players who play when the other team has the possession of the ball. Because of the body contact players have during the game, helmets are worn to protect their head and face area, whereas pads are worn to protect the shoulders, arms, and legs. Also, there are officials carrying whistles and flags to make certain that the rules of the game are followed during the game. The football is made of leather and is brown in colour. It is shaped much like an oval and has white rings near each end of the football. These rings help the players see the ball when it is thrown or someone is running with it. The eight stitches on the top of the football help the players to grip the ball when throwing or passing. The most famous game of the year is Super Bowl that is played in January or February. It is televised around the world and is watched by millions of people each year.

What do officials do during the game of football?

Find the word which has a different sound in the part underlined

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Was radium ____ by Marie Curie?

The ______ effect of the new policy is that the farmer is now working for himself, and not for the state sake.

(291)______

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In ancient times, some of the first celebrities were Roman gladiators. Rather like today’s TV talent-show contestants, these men fought each other for the audience’s entertainment. Fast forward to the 18th century, it was politicians and preachers who were able to become celebrities through public (1)__________. George Whitefield, for example, a preacher from England, (2)___________ a crowd of 30,000 when he visited the US city of Boston. It’s no wonder he was called ‘Anglo-America’s first modern celebrity’. In the 19th century, the arrival of cheap newspapers created a sudden (3)___________ for exciting stories. All kinds of people began to get their 15 minutes of fame, including the legendary American outlaw and bank robber, Jesse James, and one of the world’s first media celebrities, Sam Patch. Patch became famous for jumping into rivers from high places, and he became a (4)___________ name by leaping into Niagara Falls. He survived every jump, except the last one into the Genesee River in New York. In the same way that the media is held (5)___________ for celebrity problems today, people blamed the pressure of the media for Patch’s sudden end.

Rewrite the sentence
It’s fascinating to watch science fiction movies.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions :
A Healthy Way To Know A City
Maybe you are staying in a city, and there is no park nearby where you can take your morning job. One of the more recent trend is to go on a running tour, but you are not leading the way. Rather, a running (1)_________ who knows the best (2)_________ in the city acts as your guide. You are going out for a run, but you are also being shown highlights of the city while you are doing it. Guided running tours are a trend that seems to be catching (3)_________ in quite a few of the bigger cities in the United States. New York City, Chicago,  and San Francisco are just three of the major cities that have running tours in (4)_________. They offer these tours to individuals, groups, and even for corporate events. If you are going into a city with colleagues to attend a business meeting or a convention, what better way is there to see the city and network with others (5)_________ while taking a healthy run?

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It was an_________ day.