Today, many people use plants from other places to design their yards. Well, do they have any influence on animals living nearby? As we know, plants supply food for things like insects and plant-eating animals. In turn, birds and meat-eating animals feed on these insects and plant-eating animals. It is easy to see how important plants are.

    Although foreign plants may look beautiful, they can cause problems when there are too many of them. I live in Virginia, USA, and sometimes see a plant—commonly known as Kudzu—that seems to cover everything in the area, even climbing over whole trees and houses.

    Kudzu is an unbelievable plant since it grows very fast. It was first brought to the United States from south-east Asia around the 1870's as a crop that farmers could grow. However, Kudzu quickly came to be considered harmful throughout the southern United States.

    Since Kudzu grows fast in many different environments, it can completely cover areas of land quickly. The plant is also not eaten by any insects or birds in the United States so it can grow unchecked. Kudzu can cover trees, bushes, and even houses. It costs the United States 500 million dollars a year to just keep Kudzu from growing too fast. The plant is a perfect example of what scientists call an invasive (侵略性的) species, which grows more quickly than other native plants.

    All foreign plants have the possibility to spread quickly. Not only are they costly, but planting them in gardens actually takes away food from insects. If everyone filled their garden with plants native to where they live, many lovely butterflies and other native creatures would be attracted to their backyards! So, take a look out of your window — how does your garden grow?

阅读下列短文，从每题所给的四个选项 （A 、B 、C  和 D ）中，选出最佳选项。

    The ancient city of Xi'an in China holds many treasures. And last month, archaeologists working there made an important discovery—a buried palace built in the third century B.C. to honor China's first emperor.

    The entire palace measures roughly 2,260 feet long by 820 feet wide. It includes 10 courtyard houses and one main building. Archaeologists found bricks and pieces of pottery at the site of the palace, as well as the remains of walls and roads.

    The palace is part of the massive burial complex of Emperor Qin Shihuangdi. He conquered seven warring kingdoms and united ancient China in 211 B.C.

    Qin Shihuangdi wanted his legacy, or accomplishments, to be remembered forever. So he hired more than 700,000 workers to build his funeral complex in Xi'an. It represents a miniature version of his vast kingdom.

    The complex also includes the world-famous terra-cotta army, a collection of more than 8,000 life-size clay statues. These sculptures represent soldiers, acrobats, and horses from the Qin Dynasty (221 B.C.-206 B.C.). Scientists have not yet found all these terra-cotta warriors, even though they discovered more of the statues last summer.

    Farmers discovered the complex by accident in 1974. Since then, scientists studying the site have learned a great deal about life in ancient China. But much of the emperor's tomb has yet to be dug up, or unearthed. Many of the artifacts (objects from the past) are so old that scientists cannot preserve them.

    "Archaeologists fully acknowledge that nobody in the world has the technology (to safely dig up Xi'an's treasures) yet," explains Kristin Romey, an expert on Chinese archaeology.

    But as technology improves, archaeologists will keep digging to uncover the rest of the wonders that still lie buried in Xi'an.

    "It's one of the most important archaeological discoveries that's waiting to be made," says Romey, "and we know where it is."

    British Airways booking secrets-and the best late deals this week: Short holidays and European city breaks.

    Dublin from $ 109 pp: Enjoy the Emerald Isle without the St Patrick's Day crowds. Departing 20th March, this package includes a two night stay at the four-star Kings Wood Hotel Citywest and return flights from London Stansted. Click here.

    Bruges from $ 159 pp: Treat mum to a mother's day city break in the medieval, fairly-tale town of Bruges and enjoy canal-side strolls and a nice helping of culture. Price includes two nights at the four-star NH Brugge with travel from London St Pancras, departing 20^th March. Click here.

    Madrid from $ 166 pp: Fly from Liverpool on March 27 for three nights' B& B at the three-star Espahotel Plaza de Espana. Real Madrid don't have a football game then, so sec if Ronaldo fancies a cerveza. Click here.

    French Alps from $ 499 pp: Save over $ 320 each on a week's skinning at Les Arcs 2000, staying catered at the Chalet Vanoise. Based on two sharing and includes flights from Manchester on March 18 and transfers. Six-day lift passes from $ 219, equipment hire from $ 65. Click here.

    Tenerife from $ 289 pp: Get your tan on early with a trip to the European home of beaches: Tenerife, with its postcard perfect golden sand. Spend seven nights at the four-star Hotel Spa La Quinta Park Suites, departing 6^th May and including return flights. Click here.

    The bristlecone pine (狐尾松) is one of the longest-living things on Earth. These trees, with their strangely shaped branches, can live up to 5,000 years, but experts worry that a warming climate in some areas may threaten its future.

    Researchers say warmer weather is permitting a similar kind of tree, the limber pine (柔枝松), to take over good growing places from the ancient bristlecone. They say the tree is being forced out of mountainous areas where it grows.

    Scientists at the University of California, Davis, say climate change is causing the trees to compete with each other.

    Brian Smithers led the research project. “The limber pine is taking all the good spots,” he said.

    Bristlecone pines grow in high mountain forests in eastern California, Nevada and Utah. In the mountains, they face high winds and extreme temperatures.

    The difficult conditions leave the trees with twisted(变形的) branches and shapes. To survive long periods without water, parts of the trees die, including much of their outer bark (外皮). This makes the trees appear dead, except for small green pine needles. They show that the tree is indeed alive.

    The oldest living bristlecone pine is somewhere in California. It is not marked in any special way, so that people do not try to damage it.

    The limber pine is the bristlecone's distant relative and competitor, which can also live a long time — up to 2,000 years. Researchers say it is found at lower elevations (纬度), where temperatures are warmer.

    The scientists at the University of California, Davis, recently released the results of a three-year study. Their research centered on trees that have started growing in the last 50 years in the Great Basin area of California's White Mountains. The researchers found that most of the trees growing at higher elevations were limber pines.

    Smithers said, “It's very strange to see it charging higher up and not see the bristlecone charging up the mountain slopes ahead of the limber pine.”

    Smithers said the bristlecones are not in danger of disappearing, but he thinks they could be forced out of some places where they have grown for thousands of years.

    There were smiling children all the way. Clearly they knew at what time the train passed their homes and they made it their business to stand along the railway, wave to complete strangers and cheer them up as they rushed towards Penang. Often whole families stood outside their homes and waved and smiled as if those on the trains were their favorite relatives. This is the simple village people of Malaysia. I was moved.

    I had always traveled to Malaysia by plane or car, so this was the first time I was on a train. I did not particularly relish the long train journey and had brought along a dozen magazines to read and reread. I looked about the train. There was not one familiar face. I sighed and sat down to read my Economics.

    It was not long before the train was across the Causeway and in Malaysia. Johore Baru was just another city like Singapore, so I was tired of looking at the crowds of people as they hurried past. As we went beyond the city, I watched the straight rows of rubber trees and miles and miles of green. Then the first village came into sight. Immediately I came alive; I decided to wave back.

    From then on my journey became interesting. I threw my magazines into the waste basket and decided to join in Malaysian life. Then everything came alive. The mountains seemed to speak to me. Even the trees were smiling. I stared at everything as if I was looking at it for the first time.

    The day passed fast and I even forgot to have my lunch until I felt hungry. I looked at my watch and was surprised that it was 3:00 pm. Soon the train pulled up at Butterworth. I looked at the people all around me. They all looked beautiful. When my uncle arrived with a smile, I threw my arms around him to give him a warm hug (拥抱). I had never done this before. He seemed surprised and then his weather-beaten face warmed up with a huge smile. We walked arm in arm to his car.

    I looked forward to the return journey.

Dear Durhammers,

    Durham has been your home in the past three years. This is an appropriate moment in time to invite you as a group of "tourists" in this special exploration. We would also like to congratulate you on your forthcoming transition from being a Durhammer to a member of society. Please see information below on offers and activities to assist with planning your coming celebrations.

    View details of special offers for Winter Assembly at:

    http://www.dur.ac.uk/ceremonies/congregation/offers/

    ●Sign up to keep in touch with Durham University and get a goody bag sponsored by the ALUMNI team.

    ●20% discount on pre-ordered Durham University Merchandise with the ticket code WGRADUATE2019 (Or you have to pay the full price at the shop.)

    ●Pre-order your photographs and receive a discounted rate.

    ●Free entry to the exhibitions at Palace Green Library for you and your guests (with tickets).

    ●Purchase a diploma container to keep your degree certificate safe. Please check:

    https://www.dur.ac.uk/student.registry/qualifications/order/

    ●Details of celebration events being held in Departments and Colleges are published at:

    https://www.dur.ac.uk/ceremonies/congregation/celebrations/

    Information on the highlight of the celebration, including but not limited to the opportunity to go out for BBQ and camping at Botantic Garden is published at:

    https://www.dur.ac.uk/campusperks/whatsnewon/ceremonies/

    We also hope very much that you will come and meet us and colleagues at the ceremony, which is a traditional and magnificent public presentation of your diploma and award, and it is always memorable and fun. You will have already received a formal email invitation, but this is just to say that we hope to meet you there and congratulate you in person.

Yours sincerely,

Sir Thomas Allen