The first two decades of this century were dominated by the microbe hunters. These hunters had tracked down one after another of the microbes responsible for the most dreaded scourges of many centuries: tuberculosis, cholera, diphtheria. But there remained some terrible diseases forwhichno microbe could beincriminated: scurvy, pellagra, rickets, beriberi. Then it was discovered that these diseases were caused by the lack of vitamins, a trace substance in the diet. The diseases could be prevented or cured by consuming foods that contained the vitamins. And so in the decades of the 1920's and 1930's, nutrition became a science and the vitamin hunters replaced the microbe hunters.
In the 1940's and 1950's, biochemists strived to learn why each of the vitamins was essential for health. They discovered that key enzymes in metabolism depend on one or another of the vitamins as coenzymes to perform the chemistry that provides cells with energy for growth and function. Now, these enzyme hunters occupied center stage.
You are aware that the enzyme hunters have been replaced by a new breed of hunters who are tracking genes-the blueprints for each of the enzymes-and are discovering the defective genes that cause inherited diseases-diabetes, cystic fibrosis. These gene hunters, or genetic engineers, use recombinant DNA technology to identify and clone genes and introduce them into bacterial cells and plants to create factories for the massive production of hormones and vaccines for medicine and for better crops for agriculture. Biotechnology has become a multibillion-dollar industry.
In view of the inexorable progress in science, we can expect that the gene hunters will be replaced in the spotlight. When and by whom? Which kind of hunter will dominate the scene in the last decade of our waning century and in the early decades of the next? I wonder whether the hunters who will occupy the spotlight will be neurobiologists who apply the techniques of the enzyme and gene hunters to the functions of the brain. What to call them? The head hunters. I will return to them later.
Almost everyone with or without a computer is aware of the latest technological revolution destined to change forever the way in which humans communicate, namely, the Information Superhighway, best exemplified by the ubiquitous Internet. Already, millions of people around the world are linked by computer simply by having a modem and an address on the 'Net', in much the same way that owning a telephone links us to almost anyone who pays a phone bill. In fact, since the computer connections are made via the phone line, the Internet can be envisaged as a network of visual telephone links. It remains to be seen in which direction the Information Superhighway is headed, but many believe it is the educational hope of the future.
The World Wide Web, an enormous collection of Internet addresses or sites, all of which can be accessed for information, has been mainly responsible for the increase in interest in the Internet in the 1990s. Before the World Wide Web, the 'Net' was comparable to an integrated collection of computerised typewriters, but the introduction of the 'Web' in 1990 allowed not only text links to be made but also graphs, images and even video. A Web site consists of a 'home page', the first screen of a particular site on the computer to which you are connected, from where access can be had to other subject related 'pages' at the site and to thousands of other computers all over the world. This is achieved by a process called 'hypertext'. By clicking with a mouse device on various parts of the screen, a person connected to the 'Net' can go travelling, or 'surfing' through a web of pages to locate whatever information is required.
Anyone can set up a site; promoting your club, your institution, your company's products or simply yourself, is what the Web and the Internet is all about. And what is more, information on the Internet is not owned or controlled by anyone organisation. It is, perhaps, true to say that no-one and therefore everyone owns the 'Net'. Because of the relative freedom of access to information, the Internet has often been criticised by the media as a potentially hazardous tool in the hands of young computer users. This perception has proved to be largely false however, and the vast majority of users both young and old get connected with the Internet for the dual purposes for which it was intended – discovery and delight.
In view of the inexorable progress in science, we can expect that the gene hunters will be replaced in the spotlight. When and by whom? Which kind of hunter will dominate the scene in the last decade of our waning century and in the early decades of the next? I wonder whether the hunters who will occupy the spotlight will be neurobiologists who apply the techniques of the enzyme and gene hunters to the functions of the brain. What to call them? The head hunters. I will return to them later.
The author implies that the most important medical research topic of the future will be
Read the text and decide that the statement is True (T), False (F) or Not Given (NG).
Although the central region of Mexico's high plateau has been inhabited for at least 20,000 years, Mexico City only dates back to the 14th century. The Aztecs, or Mexica, had reached this area in the previous century, eventually settling on an island in Lake Texcoco. Here, in 1325, the city of Tenochtitlan began to take shape.
The lake was shallow, and during the nearly 200 years until 1519, the Aztecs expanded the inhabited area by land refill and the creation of artificial islands. Canals were dug for the transportation of goods and people. Aqueducts were constructed to bring drinking water from natural springs outside the city, dams to protect it against floods, and causeways and bridges to connect the city with the shore. There were many houses, palaces, temples, squares, markets and even a zoo. Perhaps the most striking construction of this period is the Templo Mayor, a double pyramid which still survives. As the capital of an empire stretching from Texas to Honduras, Tenochtitlan was a magnificent and important city. When the Spanish arrived, they called it the 'Venice of the New World'.
The area where people lived was artificially increased between 1325 and 1519.
Read the text and decide that the statement is True (T), False (F) or Not Given (NG).
The lake was shallow, and during the nearly 200 years until 1519, the Aztecs expanded the inhabited area by land refill and the creation of artificial islands. Canals were dug for the transportation of goods and people. Aqueducts were constructed to bring drinking water from natural springs outside the city, dams to protect it against floods, and causeways and bridges to connect the city with the shore. There were many houses, palaces, temples, squares, markets and even a zoo. Perhaps the most striking construction of this period is the Templo Mayor, a double pyramid which still survives. As the capital of an empire stretching from Texas to Honduras, Tenochtitlan was a magnificent and important city. When the Spanish arrived, they called it the 'Venice of the New World'.
The Spanish began their conquest of Mexico in 1519 and came close to Tenochtitlan the same year. In 1521, they took control of it, after fierce fighting that destroyed most of the city. A new capital, with a new name, was built on the ruins, using Spanish architectural styles. One part of the lake was filled in to join the island to the shore, and Mexico City became the capital of the wealthiest colony in the Americas, the centre of trade between Spain and China.
The Aztec inhabitants of Tenochtitlan left when the city was conquered
A monarchy is a form of government where a single ruler is the head of state. It is one of the oldest forms of government in the world. Monarchs are usually kings or queens. But they can also be a chief, an emperor, or called by another name. In some countries, such as , the monarch is merely symbolic. They are figureheads with no real power. In other countries, the monarch wields considerable power. There are currently 29 sovereign monarchies around the world.
Hereditary monarchy is the most common style of succession. This form is used by most of the world's monarchies. In this case, all of the kings and queens come from the same family. A family that rules for a span of time is called a dynasty. The crown is passed down from one member to another member of the family. The hereditary system has the advantages of stability, continuity, and predictability. Family affection and loyalty are also stabilizing factors.
Read the text and choose the best answer to complete the gap.
Over the centuries, most European countries were ruled by monarchs. The , , and still have constitutional monarchies. In a constitutional monarchy a king or queen reigns but must obey the constitutional laws of the nation. This form of government severely limits the monarch's power.
In the 17th century, became a constitutional monarchy. King Charles I signed an agreement. He had to go through the English Parliament to exact new taxes and laws or to start wars. Immediately after signing the agreement, the king ignored it. He tried to rule with absolute power. He was beheaded for treason. The new era of constitutional monarchy had begun.
Almost everyone with or without a computer is aware of the latest technological revolution destined to change forever the way in which humans communicate, namely, the Information Superhighway, best exemplified by the ubiquitous Internet. Already, millions of people around the world are linked by computer simply by having a modem and an address on the 'Net', in much the same way that owning a telephone links us to almost anyone who pays a phone bill. In fact, since the computer connections are made via the phone line, the Internet can be envisaged as a network of visual telephone links. It remains to be seen in which direction the Information Superhighway is headed, but many believe it is the educational hope of the future.
The World Wide Web, an enormous collection of Internet addresses or sites, all of which can be accessed for information, has been mainly responsible for the increase in interest in the Internet in the 1990s. Before the World Wide Web, the 'Net' was comparable to an integrated collection of computerised typewriters, but the introduction of the 'Web' in 1990 allowed not only text links to be made but also graphs, images and even video. A Web site consists of a 'home page', the first screen of a particular site on the computer to which you are connected, from where access can be had to other subject related 'pages' at the site and to thousands of other computers all over the world. This is achieved by a process called 'hypertext'. By clicking with a mouse device on various parts of the screen, a person connected to the 'Net' can go travelling, or 'surfing' through a web of pages to locate whatever information is required.
Anyone can set up a site; promoting your club, your institution, your company's products or simply yourself, is what the Web and the Internet is all about. And what is more, information on the Internet is not owned or controlled by anyone organisation. It is, perhaps, true to say that no-one and therefore everyone owns the 'Net'. Because of the relative freedom of access to information, the Internet has often been criticised by the media as a potentially hazardous tool in the hands of young computer users. This perception has proved to be largely false however, and the vast majority of users both young and old get connected with the Internet for the dual purposes for which it was intended – discovery and delight.
To what does pronoun "IT" in the passage refer?
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