1 . The West Potomac Park in Washington, DC, lies just west of the National Mall. It is home to some of Washington’s most iconic (标志性) sites. But the park’s most famous attraction? Cherry blossoms.
Thousands of cherry trees bloom around the waters of the Tidal Basin (潮汐湖), which reflect the trees’ images. The basin was created in the late1800s to prevent the Potomac River from flooding. The original cherry trees were a gift from Japan. On March 26, 1912, more than 3, 000 cherry trees arrived in Washington. Most were planted around the Tidal Basin. But cherry trees were also planted near the Washington Monument and the White House.
Mike Litterst, a spokesperson for the U. S. National Park Service, which maintains the West Potomac Park, helps protect the cherry trees. “This wonderful gift is over 100 years old now and, if you will, the gift keeps on giving. You can enjoy its beauty every year”.
The cherry blossoms also serve as a symbol of the beginning of springtime. Every year, Washington celebrates the arrival of spring with a two - week Cherry Blossom Festival. More than 1.5 million people from around the world visit the nation’s capital during the festival. They all hope to see the cherry trees at their “peak (高峰) bloom”,which lasts several days each year. Experts begin making peak bloom predictions in February. Visitors make their travel plans to Washington based on these predictions. Last year, officials correctly predicted the peak bloom six weeks in advance. But this year, unpredictable weather in March in Washington has made guessing it difficult. “Peak bloom” dates have changed many times.
The cherry blossoms have also become a worldwide symbol of Washington itself. BoWen moved to Washington from China seven years ago. He comes to the Cherry Blossom Festival. “It’s so famous. Everywhere you can see Washington DC Cherry Blossom Festival, on like Twitter and Instagram.”
1. What do we learn about the West Potomac Park?| A．It is just next to the Tidal Basin. | B．There are some iconic sites around it. |
| C．It includes a man - made body of water. | D．All the cherry trees from Japan were there. |
| A．The old cherry trees are still in blossom. | B．Visitors can pick the flowers if they like. |
| C．Japan is still giving them the cherry trees. | D．Visitors want to have the cherry trees as a gift. |
| A．It usually lasts one week. | B．Its time is not the same every year. |
| C．It is held when cherry trees start to bloom. | D．Its celebration is held all over the country. |
| A．It can be enjoyed just online. | B．It is liked by the Chinese very much. |
| C．It is one of the most important ones. | D．It is widely known all over the world. |
2 . How to Control Weeds When Planting
No matter what you choose to grow in the garden, at some point, you will have to deal with unwanted plants, known as weeds.
It is important to note that some weeds are not all bad. In fact, you can eat them. Dandelions (蒲公英) are also viewed as a weed by many people.
However, left to grow on their own, weeds can take over a garden. To slow the growth of weeds, add a layer of weed-free, organic material to the top of your garden, around the plants.
A simple and effective method of weed control is to break up the surface layer of the soil. But you must do this regularly. Do not turn the soil over.
| A．But their leaves are also full of nutrients. |
| B．This makes it difficult to reshape a garden. |
| C．A weed is just a plant growing in the wrong place. |
| D．This improves the soil and keeps weeds from growing. |
| E．Besides being unwanted, what else do weeds do to a garden? |
| F．Buried in the soil are weed seeds, waiting for the right conditions. |
| G．So, before we hurry outside to kill all the weeds, consider their good side. |
3 . French adventurer-scientist Roland Bourdeix has a grand vision for how to preserve a thousand or more genetic varieties of coconut trees. Imagine, as he does, turning dozens or hundreds of remote Pacific islands into coconut sanctuaries. Each island would contain just a few varieties of these trees.
But why? Are coconut trees, the source of oil and newly trendy coconut water, somehow in danger?
Not exactly. At least not for now. There are plenty of coconut palms all over the tropics, and coconut production has been slowly growing. But that masks a potential long-term problem, says Stephan Weise, Deputy Director General for Research at Bioversity International in Rome. Most coconut production comes from a small part of the coconut’s gene pool (基因库). Producers rely on a handful of high-producing varieties or hybrids (杂交品种). Those commercial varieties are slowly overwhelming (压倒)traditional varieties that people in the tropics have grown thousands of years. Those are the storehouse of the coconut’s genetic diversity: All of the colors, shapes, tastes, and survival tools that this species possesses — and may need again someday.
Conserving (保护)such diversity in agricultural crops is a familiar problem, but the situation with coconuts is a little bit different, Weise says.
First of all, scientists can’t yet preserve a particular kind of coconuts in refrigerated “gene banks,” as they do with standard seeds. They can’t dry, freeze, and preserve coconuts for decades. Instead, coconuts have to be preserved as living trees, growing outside.
This leads to the second problem. Coconut varieties growing in the open air often won’t reproduce themselves successfully. Their flowers pick up pollen (花粉)from other trees nearby, which often turn out to be commercial varieties or hybrids. And when that happens, some genes may be lost altogether.
So what’s the secret to preserving these coconuts? For starters, scientists have set up a dozen open-air coconut gene banks. They’re reproducing each variety through careful hand-pollination of the trees. But Weise says that’s expensive and labor-intensive.
This brings us back to Roland Bourdeix’s crazy-sounding idea. The key to preserving coconut biodiversity more cheaply, he thinks, is isolation. And there’s no more isolated place than a lonely Pacific island. Just convince people on one of these islands to plant coconut trees from a single variety, and the problem is practically solved. He’s found several islands where the inhabitants are willing to help turn his vision into reality. One of them is well-known already: The Tetiaroa Atoll in French Polynesia, an idyllic retreat once owned by Marlon Brando.
1. Why is it important to preserve the traditional varieties of coconut?| A．The traditional varieties are more commercial. |
| B．They can help explain the history of people living in the tropics. |
| C．They contain genetic diversity. |
| D．It can help the tourism on remote Pacific islands. |
| A．They freeze them. | B．They hand-pollinate them. |
| C．They grow them out of labs. | D．They mix them with other breeds. |
| A．They are owned by celebrities, which can help promote public awareness of the issue. |
| B．They are among the most isolated places in the world. |
| C．The inhabitants on the islands are innocent enough to be deceived. |
| D．The labor on those islands is cheaper. |
| A．A Crazy Gardener |
| B．Remote Islands for Preserving Coconut Genes |
| C．Advantages of Traditional Coconut Trees |
| D．Loss of Coconut Genes |
4 . Greenhouse gas emissions would rise if all farms in England and Wales went organic. Though the emissions of each farm would go down, much more food would have to be imported, as the amount they would produce would decrease greatly.
“The key message from my perspective is that you can't really have your cake and eat it,” says Laurence Smith, now at the Royal Agricultural University in the UK, who was part of the team that ran the numbers. Smith is a supporter of organic farming and says “there are a lot of merits of the organic approach”, but his analysis shows that organic farming has downsides too.
Farming and changes in land use, such as cutting down forests, are responsible for a third of all greenhouse gas emissions. That means reducing farming emissions and the land needed for farming is required to limit further global warming.
Smith and his colleagues found that emissions per unit of food are, on average, 20 per cent lower for organic crops and 4 per cent lower for organic animal products. However, organic harvests per hectare (公顷) are also lower on average. For wheat and barley, for instance, harvests are just half of those of conventional farms. This means 1.5 times as much land would be needed to grow the same amount of these foods.
The estimated increase in emissions varies greatly, depending on where the extra farmland comes from. If only half comes from turning grassland into farms, the increase could be as low as 20 per cent. If grassland that would otherwise have been reforested is turned into farmland, emissions could nearly double.
This doesn't necessarily mean people should stop eating organic produce, says Smith. People might choose organic food for other reasons, such as to reduce their pesticide exposure (though contrary to popular belief, organic farmers do use pesticides) or for the sake of wildlife.
Going 100 per cent organic could also harm global biodiversity. The extra land used for farming would mean the land available for wildlife would be smaller and more fragmented (碎片化的).
Smith says the best option may be to use some organic and conventional farming methods at the same time.
1. Why may greenhouse gas emissions increase if a country goes organic?| A．Organic farms take longer to build. |
| B．The agricultural output will increase greatly. |
| C．The emissions of each farm unit will increase. |
| D．Greater demand for imported food will be created. |
| A．Changes. | B．Challenges. | C．Advantages. | D．Differences. |
| A．Organic harvests per unit are greater than traditional harvests. |
| B．Organic farming needs more farmland to feed a country. |
| C．Global warming could be brought under control. |
| D．Land was not used in a responsible way. |
| A．Stopping using pesticides. |
| B．Eating less organic produce. |
| C．Going back to traditional farming. |
| D．Adopting mixed farming methods. |
5 . Plants don’t have ears or a central nervous system, but new research out of the University of Missouri has demonstrated that they might still have the ability to “hear”. More specifically, plants have been shown to exhibit an immune (免疫) response to the mere sound of a hungry insect.
For the study, researchers played the sound of a caterpillar chewing to a group of plants, which caused slight vibrations (振动) on the plants’ leaves. The plants were able to recognize these vibration patterns as danger, and responded by mounting the appropriate immune response. In other words, it appears that plants can “hear” themselves being chewed on.
Researchers assume that plants achieve this remarkable ability thanks to proteins that respond to pressure found within their cell membranes. Vibrations cause pressure changes within the cell, which can change the behavior of the proteins; however, additional study will be required to confirm or deny this theory.
Once researchers identify the exact mechanisms at play in this process, it could lead to advances in crop protection. Farmers could potentially learn to use sound to cause a plant’s natural chemical defenses against insect threats, rather than turning to poisonous chemicals.
“We can imagine applications of this where plants could be treated with sound or genetically engineered to respond to certain sounds that would be useful for agriculture,” said study author Heidi Appel.
The study adds to the growing list of ways that plants have been shown to sense their environments. They are not the boring organisms that many people assume they are. For instance, some plants are able to communicate with each other and signal upcoming danger to their neighbors by releasing chemicals into the air. Plants can respond to light (think about sunflowers) and temperature. Some can even respond to touch, such as the Venus flytrap (捕蝇草), which snaps shut when an insect stimulates its hairs.
1. Why did researchers carry out the study?| A．To find out if plants can react to sounds. |
| B．To learn how plants recognize dangers. |
| C．To discover if plants can shake their leaves. |
| D．To see how plants improve immune systems. |
| A．To remove insects. | B．To protect crops. |
| C．To treat plant diseases. | D．To produce chemicals. |
| A．There are more plants than we know. |
| B．Plants are more active than we think. |
| C．Plants fit in well with their environments. |
| D．Lots of secrets about plants remain unclear. |
| A．Can plants “talk” with each other? |
| B．How do plants make use of sounds? |
| C．Can plants “hear” themselves being eaten? |
| D．How do plants defend themselves against attacks? |
6 . For many people, catching a smell of freshly cut grass is a pleasant sign that warmer weather is here to stay. For the grass, however, this scent signals an entirely different story.
The smell we associate with freshly cut grass is actually a chemical SOS, one used by plants to beg nearby creatures to save them from attack. After all, when danger strikes —whether it's gardening equipment or a hungry caterpillar — plants can't lift their roots and run. They must fight where they stand. To protect themselves, plants employ a string of molecular (分子) responses. These chemical communications can be used to poison an enemy, warn surrounding plants of dangers or attract helpful insects to perform needed services.
Clearly, plants can communicate. But does that mean they can feel pain? According to some researchers, plants release gases that are the equivalent of crying out in pain. Using a laser-powered microphone, researchers have picked up sound waves produced by plants releasing gases when cut or injured. Although not audible to the human ear, the secret voices of plants have revealed that cucumbers scream when they are sick, and flowers cry when their leaves are cut.
There's also evidence that plants can hear themselves being eaten. Researches show that plants understand and respond to chewing sounds made by caterpillars dining on them. As soon as the plants hear the noises, they respond with several defense mechanisms.
For some researchers, evidence of these complex communication systems — giving out noises via gas when in pain — signals that plants feel pain. Others argue that there cannot be pain without a brain to register the feeling. Still more scientists infer that plants can exhibit intelligent behavior without possessing a brain or conscious awareness.
As they grow, plants can change their paths to avoid obstacles or reach for support with their tendrils (卷须). This activity comes from a complex biological network distributed through the plants' roots, leaves and stems. This network helps plants reproduce, grow and survive.
1. What does the smell of freshly cut grass signal?| A．Warmer weather. | B．Being poisonous. |
| C．Cry for help. | D．The need of services. |
| A．By giving out gases. | B．By changing the color of their leaves. |
| C．By producing audible sound waves. | D．By sharing it through the root systems. |
| A．Their tendrils. | B．Their biological network. |
| C．Their communication systems. | D．Their conscious awareness. |
| A．Do plants feel pain? | B．How plants protect themselves? |
| C．Do plants communicate? | D．How plants grow and reproduce? |
