There’s nothing more welcoming than a door opening for you. 1 the need to be touched to open or close, automatic doors are essential in 2 disabled access to buildings and helping provide general 3 to commercial buildings.
Self-sliding doors began to emerge as a commercial product in 1960 after being invented six years 4 by Americans Dee Horton and Lew Hewitt. They 5 as a novelty feature, but as their use has grown, their 6 have extended within our technologically advanced world. Particularly 7 in busy locations or during times of emergency, the doors 8 crowd management by reducing the obstacles put in people’s way.
9 making access both in and out of buildings easier for people, the difference in the way many of these doors open helps reduce the total area 10 by them. Automatic doors often open to the side, with the panels sliding across one another. Replacing swing doors, these 11 smaller buildings to maximise the usable space inside without having to 12 the way for a large, sticking-out door. There are many different types of automatic door, with each 13 specific signals to tell them when to open. 14 these methods differ, the main 15 remain the same.
Each automatic door system 16 the light, sound, weight or movement in their vicinity as a signal to open. Sensor types are chosen to 17 the different environments they are needed in. 18 , a busy street might not 19 a motion-sensored door, as it would constantly be opening for passers-by. A pressure-sensitive mat would be more 20 to limit the surveyed area. 2

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Nearly 2,000 years ago, as the Romans began to pull out of Scotland, they left behind a curious treasure:10 tons of mails, nearly a million of the things. The nail hoard was discovered in 1960 in a four-metre-deep pit covered by two metres of gravel.
Why had the Romans buried a million nails? The likely explanation is that the withdrawal was rushed, and they didn’t want the local Caledonians getting their hands on 10 tons of weapon-grade iron. The Romans buried the nails so deep that they would not be discovered for almost two millennia.
Later civilisations would value the skilled blacksmith’s labour in a nail even more than the raw material. As Roma Agrawal explains in her new delightful book Nuts and Bolts, early 17th-century Virginians would sometimes bum down their homes if they were planning to relocate.
This was an attempt to recover the valuable nails, which could be reused after sifting the ashes. The idea that one might bum down an entire house just to reclaim the nails underlines how scarce, costly and valuable the simple-seeming technology was.
The price of nails fell by 90% between the late 1700s and mid-1900s,as economist Daniel Sichel points out in a research paper. According to Sichel, although the falling price of nails was driven partly by cheaper iron and cheaper energy, most of the credit goes to nail manufacturers who simply found more efficient ways to turn steel into nails.
Nails themselves have changed over the years, but Sichel studied them because they haven’t changed much. Roman lamps and Roman chariots are very different from LED strips and sports cars, but Roman nails are still clearly nails. It would be absurd to try to track the changing price of sports cars since 1695, but to ask the same question of nails makes perfect sense.
I make no apology for being obsessed by a particular feature of everyday objects their price. I am an economist, after all. After writing two books about the history of inventions, one thing I’ve learnt is that while it is the enchantingly sophisticated technologies that get all the hype, it’s the cheap technologies that change the world. 4
The Gutenberg printing press transformed civilisation not by changing the nature of writing but by changing its cost—and it would have achieved little without a parallel collapse in the price of surfaces to write on, thanks to an often-overlooked technology called paper. Solar panels had a few niche uses until they became cheap; now they are transforming the global energy system.

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(41) Hannah
Simply, there are people in Nigeria who cannot travel to the Smithsonian Institution to see that part of their history and culture represented by the Benin Bronzes. These should be available to them as part of their cultural heritage and history and as a source of national pride. There is no good reason that these artifacts should be beyond the ordinary reach of the educational objectives or inspiration of the generations to which they were left. They serve no purpose in a museum in the United States or elsewhere except as curious objects. They cannot be compared to works of art produced for sale which can be passed from hand to hand and place to place by purchase.
(42) Buck
We know very exact reproductions of artwork can be and are regularly produced. Perhaps museums and governments might explore some role for the use of nearly exact reproductions as a means of resolving issues relating to returning works of art and antiquities. The context of any exhibit is more important to me than whether the object being displayed is 2,000 years old or 2 months old. In many cases the experts have a hard time agreeing on what is the real object and what is a forgery. Again, the story an exhibit is trying to tell is what matters. The monetary value of the objects on display is a distant second place in importance.
(43) Sara
When visiting the Baltimore Museum of Art, I came across a magnificent 15th-century Chinese sculpture. It inspired me to learn more about the culture that it represented. Artifacts in museums have the power to inspire, and perhaps spark that need to learn and understand the nature of their creators. Having said that, I do feel that whatever artifacts find their way to public museums should, in fact, be sanctioned as having been obtained on loan, legally purchased, or obtained by treaty. Stealing artifacts from other peoples ’ cultures is obscene; it robs not only the physical objects, but the dignity and spirit of their creators.
(44) Victor
Ancient art that is displayed in foreign countries by all means should be returned to the original country. The foreign countries have no right to hold back returning the items. I would ask that the foreign nations and the original country discuss the terms of transfer. Yes, there is the risk that the original country will not have as good security as do the foreign countries. But look at what happened to Boston’s Gardner Museum theft in 1990, including the loss of Rembrandt, Vermeer, Manet, and other masterpieces. Nothing is absolutely safe, nowhere. And now Climate Change agitators are attacking publicly displayed works in European museums.
(45) Julia
To those of you in the comments section who are having strong feelings about artifacts being removed from cities in the US and Britain and returned to their countries of origin, I would ask you to consider: why do you think Americans have more of a right to easily access the Benin Bronzes than the people of Nigeria? Why are people who live within a day’s drive of London entitled to go and see the Elgin Marbles whenever they want, but the people of Athens aren’t? What intrinsic factors make the West a suitable home for these artifacts but preclude them from being preserved and displayed by their countries of origin? If your conclusion is that the West is
better able to preserve these artifacts, think about why you’re assuming that to be true.

A.It is clear that the countries of origin have never been compensated for the stolen artifacts.

B. It is a flawed line of reasoning to argue against returning artifacts to their countries of origin.

C. Museum visitors can still learn as much from artifacts ’ copies after the originals are returned.

D. Reproductions, even if perfectly made, cannot take the place of the authentic objects.

E. The real value of artifacts can only be recognized in their countries of origin rather than anywhere else.

F. Ways to get artifacts from other countries must be decent and lawful.

G. Concern over security is no excuse for refusing to return artifacts to their countries of origin.

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“Elephants never forget”—or so they say—and that piece of folklore seems to have some foundation.
The African savanna elephant, also known as the African bush elephant, is distributed across 37 African countries. They move between a variety of habitats, including forests, grasslands, woodlands, wetlands and agricultural land. (46) They sometimes travel more than sixty miles to find food or water, and are very good at working out where other elephants are—even when they are out of sight. Using tracking devices, researchers have shown that they have “remarkable spatial acuity.” When finding their way to waterholes, they headed off in exactly the right direction, on one occasion from a distance of roughly thirty miles. What is more, they almost always seem to choose the nearest waterhole. (47) The researchers are convinced that the elephants always know precisely where they are in relation to all the resources they need, and can therefore take shortcuts, as well as following familiar routes.
Although the cues used by African elephants for long-distance navigation are not yet understood, smell may well play apart.
Elephants are very choosy eaters, but until recently little was known about how they selected their food. (48) One possibility was that they merely used their eyes and tried out the plants they found, but that would probably result in a lot of wasted time and energy, not least because their eyesight is actually not very good.
(49) The volatile chemicals produced by plants can be carried a long way, and they are very characteristic: Each plant or tree has its own particular odor signature. What is more, they can be detected even when they are not actually visible. New research suggests that smell is a crucial factor in guiding elephants—and probably other herbivores—to the best food resources.
The researchers first established what kinds of plant the elephants preferred either to eat or avoid when foraging freely. They then set up a “food station” experiment, in which they gave the elephants a series of choices based only on smell. (50) The experiment showed that elephants may well use smell to identify patches of trees that are good to eat, and secondly to assess the quality of the trees within each patch. Free-ranging elephants presumably also use this information to locate their preferred food.
Their well-developed hippocampal structures may enable elephants, like rats and people, to construct cognitive maps.

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Directions：
Read the following email from an international student and write a reply.
Dear Li Ming, I’ve got a class assignment to make an oral report on an ancient Chinese scientist, but I’m not sure how to prepare for it. Can you give me some advice? Thank you for your help. Yours, Paul Write your answer in about 100 words on the ANSWER SHEET.
Do not use your own name in your email; use “Li Ming” instead. (10 points)

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Directions：
Write an essay based on the picture and the chart below. In your essay, you should 1) describe the picture and the chart briefly, 2) interpret the implied meaning, and 3) give your comments.
Write your answer in 160-200 words on the ANSWER SHEET. (20 points)

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