Plants can’t communicate by moving or making sounds, as most animals do. Instead, plants produce volatile compounds (挥发性化合物) —— chemicals that easily change from a liquid to a gas. A flower’s sweet smell, for example, comes from such volatile compounds to attract insects such as bugs and bees.
Plants can also discover volatile compounds produced by other plants. A tree under attack by hungry insets, for instance, may give off these chemicals in order to let other trees know about the attack. In response, the other trees may send off their chemicals to keep the bugs away —— or even chemicals that will attract the bugs’ natural enemies.
Now scientists have created a quick way to understand what plants are saying: a chemical sensor (传感器) called an “electronic nose”. The “e-nose” can tell such compounds as plants make. When plants are attacked, scientists say, the e-nose could help quickly decide whether plants are being eaten by insects. But today, the only way to spot such insects is to inspect individual plants by observing them. This is a challenging task for managers of greenhouses, including those that can house thousands of plants. The research team is working with an e-nose that can recognize volatile compounds. Inside the device, 13 sensors chemically react with volatile compounds based on the interactions (相互作用), and then the e-nose will give off electronic signals that the scientists can analyze by using computer software.
To test the e-nose, the team presented it with healthy leaves from cucumber, pepper and tomato plants, all being common greenhouse crops. Then scientists collected samples of the air around damaged leaves from each type of crop. These plants had been damaged either by insects or by scientists who made holes in the leaves with a hole punch (打孔器).
The e-nose, it turns out, can identify healthy cucumber, pepper and tomato plants based on the volatile compounds they produce. It could also identify tomato leaves that had been damaged. But even more impressive, the device could tell which type of damage —— by insects or with a hole punch —— had been done to the tomato leaves.
With some fine-tuning (微调), a device like the e-nose can one day be used in greenhouses to quickly spot harmful bugs, the researchers say. A device like this can also be used to identify fruits that are perfectly ripe and ready to pick and eat, says Natalia Dudareva, a biochemist at Purdue University in West Lafayette, India, who studies smells of flowers and plants. Hopefully, scientists believe, the device can bring large benefits to greenhouse managers in the near future.
1.We learn from the text that plants communicate with each other by ______.
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A．making some sounds |
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B．waving their leaves |
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C．producing some chemicals |
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D．sending out electronic signals |
2.What did the scientists do to find out if the e-nose worked?
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A．They fixed 13 sensors inside the device. |
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B．They presented it with all common crops. |
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C．They collected different damaged leaves. |
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D．They do tests on damaged and healthy leaves. |
3.According to the writer, the most amazing thing about the e-nose is that it can ______.
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A．pick out ripe fruits quite expertly |
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B．spot the insects in a very quick way |
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C．tell different damages to leaves |
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D．recognize unhealthy tomato leaves |
4.We can infer from the last paragraph that the e-nose ______.
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A．is unable to tell the smell of flowers |
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B．is not yet tested in greenhouses |
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C．is designed by scientists at Purdue |
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D．is helpful in killing harmful insects |
When I was seven, my father gave me a Timex, my first watch. I loved it, wore it for years, and haven’t had another one since it stopped ticking a decade ago. Why? Because I don’t need one. I have a mobile phone and I’m always near someone with an iPod or something like that. All these devices (装置) tell the time — which is why, if you look around, you’ll see lots of empty wrists (手腕); sales of watches to young adults have been going down since 2007.
But while these wise people have realized that they don’t need them, others — including some distinguished ones of our time — are spending total fortunes on them. Brands such as Rolex, Patek Philippe and Breitling command shocking prices, up to £ 250.000 for a piece.
This is ridiculous. Expensive cars go faster than cheap cars. Expensive clothes hang better than cheap clothes. But these days, all watches tell the time as well as all other watches. Yes, you may say expensive watches will come with some extra functions — but who needs them? How often do you dive to 300 metres into the sea to test its function of waterproof, or need to find your direction in the area around the South Pole by using its compass? So why pay that much of five years’ school fees for watches that allow you to do these things?
If justice were done, the Swiss watch industry should have closed down when the Japanese discovered how to make accurate watches for a five-pound note. Instead, the Swiss re-invented the watch, with the aid of millions of pounds’ worth of advertising, as a message about the man —— usually a famous star, wearing it. Rolexes are for those who spend their weekends climbing icy mountains; a Patek Philippe is for one from a rich or noble family; a Breitling suggests you like to pilot planes across the world.
Watches are classified as “investment items” (投资项目) now. A 1994 Philippe recently sold for nearly £ 350, 000, while 1960s Rolexes have gone from 15, 000 to 30, 000 plus in a year. But, to some wealthy people, a watch is more than an investment. It’s a valuable toy for self-satisfaction, a matter of fashion. Prices may keep going up — they’ve been rising for fifteen years. But when fashion moves on, the owner of that £ 350, 000 treasured object will suddenly find his pride and joy is no more a good investment than my childhood Times.
1.The sales of watches to young people have fallen because ______.
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A．they have other devices to tell the time |
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B．they think watches are too expensive |
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C．they have little sense of time now |
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D．they prefer to wear an iPod on their wrists |
2.It seems ridiculous to the writer that ______.
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A．some people often dive 300 metres deep into the sea |
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B．expensive clothes sell much better than cheap ones |
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C．cheap cars usually don’t run as fast as expensive ones |
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D．expensive watches with unnecessary functions still sell |
3.What can be learnt about Swiss watch industry from the passage?
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A．It targets rich people as its potential customers. |
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B．It seems hard for the industry to beat its competitors. |
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C．It wastes a huge amount of money in advertising. |
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D．It is easy for the industry to re-invent cheap watches. |
4.Which would be the best title for the passage?
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A．Timex Being better than Rolex |
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B．My Expensive Childhood Timex |
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C．Super-level Watches? Not for Me! |
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D．Watches — a Valuable Collection |
Even at school there had been an unhealthy competition between George and Richard.
“I’ll be the first millionaire in Coleford!” Richard used to boast.
“And you’ll be sorry that you knew me,” George would reply “because I’ll surely be the best lawyer in our town!”
After graduation, George never became a lawyer and Richard was anybody but a millionaire …. Instead, it happened that both men opened bookshops on opposite sides of Coleford High Street, while it was hard to make much money from books then, which made the competition between them worse. Eventually, Richard closed down his, dreaming of making a fortune elsewhere.
Now, with only one bookshop in the town, business was better for George. But sometimes he sat in his narrow old kitchen and gazed out of the dirty window, thinking about his former rival (竞争对手)。Perhaps he missed him? zxxk
George was very interested in old dictionaries, and he had recently found a collector in Australia who was selling a rare first edition. When the parcel arrived, the book was in perfect condition and George was quite delighted. But while he was having lunch, George glanced at the photo in the newspaper that the book had been wrapped in. He was astonished — the smiling face was older than he remembered but unmistakable! Trembling, George started reading: “Bookends Company has bought ten bookstores from its competitors. The company, owned by multi-millionaire Richard Pike, is now the largest bookseller in this country.”
1.George and Richard were at school.
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A．roommates |
B．good friends |
C．competitors |
D．booksellers |
2.How did George feel about Richard after his disappearance?
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A．He envied Richard’s good fortune very much. |
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B．He thought about Richard from time to time. |
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C．He felt unlucky with no more rival in the town. |
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D．He was unhappy of Richard’s disappearance. |
3.George got information about Richard from .
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A．a dictionary collector in Australia |
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B．one of Richard’s competitors |
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C．some rare edition of a dictionary |
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D．the wrapping paper of a book |
4.What happened to George and Richard in the end?
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A．Both George and Richard became millionaires by selling books. |
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B．Both of them realized their original ambitions, which were the same. |
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C．George established a successful business while Richard was missing. |
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D．Richard became a millionaire while George had no great success. |
There are many different ways of seeing a town for the first time. One of them is to walk around it, guide-book 26 hand. Of course, we may 27 with our guide-books the history and 28 developments of a town and get to know them.
29 then, if we take our time and 30 in a town for a while, we may get to know it better. When we 31 it as a whole, we begin to have some 32 , which even the best guide-books do not
answer. Why is the town just 33 this —— this shape, this plan, this size? Why do its streets 34 in this particular way, and not in any 35 way?
Here even the best guide-book 36 us. One can’t find the information in it about how a town has developed to the 37 appearance. It may not describe the original 38 of a town. However, one may get some idea of what it 39 look like by walking around the town. One can also imagine 40 the town was first planned and built. Then one can learn more about in what direction the town 41 to develop.
What is the 42 of studying towns in this way？For me, it is 43 a matter that one gets a greater depth of pleasure by visiting and seeing a town with one’s own eyes. A 44 visit to a town may help one better understand why it is attractive 45 just reading about it in a guide-book.
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After the successful launching of the Shenzhou 9, ______ the astronauts will work and live in Tiangong-1— the space lab module is ______ the whole nation care about.
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A．where, what |
B．what, that |
C．that, how |
D．how, what |
The manager found that his office ______ the day before.
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A．had broken in |
B．has been broken into |
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C．had been broken into |
D．has been broken in |
