【推荐1】At first glance, the business world is no place for young women, as my co-founders and I have been told on many occasions. In spite of this pessimistic view of women’s opportunity in business, we three college-age girl with zero experience in business started off with a highly ambitious goal: to start a seaweed farm in North California, and grow as much seaweed as possible to help reduce carbon emissions (排放) and nutrient pollution from agricultural sources.

In the beginning, our ideas were either ignored or scoffed by the researchers from whom we sought help and advice. But we carried on with our research—if others wouldn’t provide us answers, we weren’t afraid to work them out ourselves. We discovered which species could grow in warmer waters, and we’d identified potential markets into which we planned to sell the products. We’ve spent the last two years setting up the first seaweed farm in NC, applying for a patent (专利) and competing with five final teams in front of the United Nations for $1 million.

Despite all our efforts, many industry experts remained unwilling to take us seriously. But as often happens in business, the same characteristics we were ignored for were, in reality, our biggest competitive advantages. Our age gave us the strength to bounce back from failure and our background as environmental scientists, rather than businesswomen, helped us find new marketing opportunities. For every 10 farmers who claimed nobody would ever want to feed their cows seaweed, we found one who was interested. For every 15 cosmetics (化妆品) producers who refused to answer our cold calls (电话推销) we stuck to the one with an interesting idea for seaweed lotion.

Over the course of our early business development efforts, we have had access to a wealth of resources, programs, and individuals who work constantly to help us succeed. By staying focused on bringing our ideas to light, our team has demonstrated that entrepreneurship (创业) is exactly the right place for the hopeful.

1. What was the major cause for their difficulty in starting business?

A．They are women.	B．They were young.
C．They lacked experience.	D．They suffered prejudice (偏见).

2. What did they do to make their business successful according to the passage?

A．They expanded their seaweed farms.

B．They experimented on seaweed species.

C．They got their product officially recognized.

D．They consulted the United Nations.

3. What is the third paragraph mainly about?

A．How they benefited from their weaknesses.

B．How they got others interested in seaweed.

C．How they made themselves more competitive.

D．How they approached potential customers.

【推荐2】Dan studied the tracks on the ground. For the third night in a row, the adult bear had returned. Was she here because she was just looking for an easy meal? Or was she here because of the baby bear locked in the pen? If that was the reason, what did she want with the cub?

Dan thought about the cub. He knew there was a lot the cub could learn from an adult bear. He did not want to disturb or interfere with the bears getting to know each other. But the cub had been brought in injured. As the cub’s guardian, Dan had a responsibility to make sure that the cub was safe. Perhaps he had been hurt by this very bear. On the other hand, what if the adult were friendly? She could teach the cub things he had to learn if he were to live in the wilderness. Dan decided it was worth taking a chance. He would let the adult bear near the cub. But he would be ready for trouble, if this turned out to be a mistake.

That night, Dan waited in the shadows near the pen. In his hand was a big flashlight. If the adult bear tried to hurt the cub, he would try to scare her off with the light. If that did not work, he had a loud horn with him. He thought that the sudden noise from the horn would drive her away.

Dan did not have to wait very long. Soon there was a rustling in the woods. Then the adult proclaimed her presence with a low growl and emerged from behind a tree. She was quick in movement and healthy. Dan hoped she would scare easily.

As soon as the cub heard her a frightening low noise, he became active and started toward the fence in an awkward run. When the two bears met at the fence, the adult stood and put her front paws against it. The cub tried to do the same, but tottered and fell forward. The adult bear snorted. Dan was not sure what the snort meant. Then the cub stuck his nose through the fence in a friendly greeting. How would the adult respond? Dan’s heart raced. He raised the flashlight and the horn, ready to act.

The adult leaned forward and gently rubbed her nose against the cub. Dan lowered the flashlight. Everything was going to be fine.

1. The author writes this passage chiefly for the purpose of_______.

A．showing people how to behave at the zoo

B．informing the reader about extinct animals

C．persuading the reader to give money to zoos

D．entertaining the reader with a story about bears

2. The author asks questions at the beginning of the story to_______.

A．help people remember the story

B．find out if the reader can answer them

C．get the reader interested in the story

D．see how much the reader knows about bears

3. Which is the closest in meaning to the underlined word “tottered” in paragraph 5?

A．Walked proudly with its head high.

B．Moved in a way that was not steady.

C．Walked with heavy steps in an angry way.

D．Moved lightly as if it was dancing.

4. Why did Dan lower the flashlight at the end of the story?

A．He saw the adult bear was not going to hurt the cub.

B．He wanted to scare away the adult bear.

C．He was concerned about what might happen.

D．He wondered if the two bears would get along well.

【推荐3】In 1996, Guan came down with a stomach illness. With the aim of strengthening his immune (免疫)system, he started running in a playground near the factory. After a little more than a year of training, he could run 10 kilometers in a very surprising time of 36 or 37 minutes.

Filled with self-confidence, he pressed on to improve his performances. Over the past 24 years, he has kept to his training program. He competed in the Beijing Marathon in 2004 and has competed in it every year since 2006. He competed in other marathons, too, His performance in the Xiamen Marathon in 2012 was particularly surprising, with a finishing time of 2:56:42, by which he became one of the most outstanding marathon runners in his age group in the country.

Being a top runner, Guan used to do exercise at least five times a week, and he would run at least 200 kilometers a month. He joined a Yuandadu Marathon Club where members could work together and get a better result with a similar training rhythm(节奏). “Training with others is particularly helpful in improving performance, " he says. As he gets older, his physical fitness has declined, but Guan has developed a stricter training plan so he can realize his 3-hour dream. Every morning he runs for 1 hour in Wanghe Park near his home, he takes part in Yuandadu's systematic running training; and he goes to Olympic Forest Park in the city's north every Sunday to run 25 to 30 kilometers as long-distance training.

“Life is a process of constantly challenging yourself and breaking through your own barriers again and again, " he says. "I'll be running until the day I can't move!”

1. Why did Guan start running?

A．To improve his immune system.

B．To prepare the running training.

C．To increase self-confidence.

D．To take part in a Marathon.

2. What made Guan draw people’ s attention in the Xiamen Marathon?

A．His particular way of running.

B．His strict training program.

C．His excellent performance.

D．His absolute confidence.

3. What can we learn about Guan from the third paragraph?

A．He trains for at least 3 hours a day

B．His hard training makes him outstanding.

C．He always fails though he is a top runner.

D．He refuses to receive systematic running training

4. Which of the following can best describe Guan?

A．Determined but mean.

B．Confident but careless

C．Humorous and helpful

D．Confident and determined

【推荐1】Universe started in the third grade when she and her father watched a blood moon — a total lunar eclipse (月食) — outside their Skokie house. “It is just really cool how the universe can change and how something like that happens,” Dobek said.

Now a seventh grader at East Prairie Elementary School, Dobek recently won the national Discovery Education Lockheed-Martin Beyond Challenge by designing a space station for traveling to Mars.

Dobek competed by handing in a two-minute video where she presents her design.

“My design will not only ensure the safety of the astronauts (宇航员) but also make sure their comfort is out of this world,” she says in her video.

Dobek’s design calls for building the Mars Storage Station to store plentiful supplies. In the video, Dobek explains how her spacecraft (宇宙飞船) — the Adventurer — will land in a space station. Dobek’s design includes physical activity for the astronauts. They can choose their exercise machines and virtual (虚拟的) reality environment. So they will be able to watch downloaded shows and even see places on Earth such as their homes.

Dobek said she began her project by performing her research and then she constructed the design over three weeks to a month, working on it whenever she could, including on weekends.

When Andrea Smeeton, her teacher, saw the video and her design before they were sent, she said she had a feeling that she could win. “I don’t know why but maybe it was the excitement and the detail in the project,” Smeeton said. “I have taught for a long time and many of my students are gifted but this project is just very creative and it gives hope to a space program.”

Dobek and her parents traveled to Washington D.C. in April where they learned Dobek had won. When she texted her teacher the happy results, Smeeton admitted that she cried.

“I want to tell other kids to follow their dreams,” Dobek said. “Whatever they want to do, they should kind of just push for it. They should always try their best.”

1. What change did Dobek show after watching the total lunar eclipse?

A．She determined to be a scientist.

B．She took to working with her father.

C．She got interested in the universe.

D．She gave up her dream of becoming an astronaut.

2. What can be learned about Dobek’s design?

A．It replaces the role of the Adventurer.

B．It enables astronauts to connect with their family.

C．It ensures the safety of the supplies in the spacecraft.

D．It aims to make life in the Mars space station comfortable.

3. How did Smeeton feel about Dobek’s design after seeing it?

A．She felt it was pretty amazing.

B．She felt it was a little disappointing.

C．She felt it was less fun than she had expected.

D．She felt it was as good as other students’ designs.

4. What kind of girl is Dobek?

A．Energetic and friendly.

B．Productive and selfless.

C．Strong-willed and generous.

D．Forward-looking and inventive.

【推荐2】Scientists say they have developed a system that uses machine learning to predict when and where lightning will strike. Researchers report the system is able to predict lightning strikes up to 30 minutes before they happen within a 30-kilometer area.

Lightning is a strong burst of electricity in the atmosphere. Since it carries an extremely powerful electrical charge, it can be destructive and deadly. European researchers have estimated that between 6,000 and 24,000 people are killed by lightning worldwide each year. For this reason, climate scientists have long sought to develop methods to predict lightning.

The system tested in the experiments uses a combination of data from weather stations and machine learning methods. The researchers developed a prediction model that was trained to recognize weather conditions that were likely to cause lightning.

The model was created with data collected over a 12-year period from 12 Swiss weather stations in cities and mountain areas. The data was placed into a unique machine learning algorithm（算法）,which compared it to records of lightning strikes. Researchers say the algorithm was then able to learn the conditions under which lightning happens.

The researchers test-ran the system several times. They found that the system made predictions that proved correct almost 80 percent of the time. "It can now be used anywhere," the Swiss Federal Institute of Technology said in a statement.

The researchers plan to keep developing the technology with a European effort that aims to create a lightning protection program. The effort is called the European Laser Lightning Rod project. Scientists working on the project are experimenting with a laser technology that could someday control lightning activity, transferring lightning charges from clouds to the ground. They hope that such technology can one day be used as protection against lightning strikes.

1. Why was the system developed?

A．To show the power of lightning.	B．To protect people from lightning.
C．To keep track of lightning deaths.	D．To meet kids’ curiosity about lightning.

2. What is special about the system?

A．It required low cost of predicting lightning.

B．It used an effective method of collecting data.

C．It was based on a number of samples worldwide.

D．It adopted a different machine learning algorithm.

3. What will the researchers do next with the laser technology?

A．Generate electricity with lightning.	B．Monitor lightning activity.
C．Direct energy from lightning.	D．Prevent the happening of lightning.

4. What can be a suitable title for the text?

A．A Theory of Employing Lightning	B．A Method of Forecasting Lightning
C．A System of Controlling Lightning	D．A Model of Creating Lightning

【推荐3】Plastic remains one of the most-used materials for making many of the things we use in our everyday lives. Things made of plastic can be very strong and last a long time. They also do well in extreme heat and cold. Plastic is also much lighter than metal and can easily be formed into different shapes. This makes the material ideal for countless uses across many different industries.

But the widespread use of plastics across the world is causing major problems for the environment. Plastic material is flooding landfills and causing severe damage in the world's oceans. Plastics can take hundreds of years to break down on their own. It has been estimated that even the most reusable kinds of plastic can only be recycled at a rate of 20 to 30 percent. Even when recycling is possible, the process is costly, can use a lot of energy and, in many cases, produces poor-quality materials.

But a team of researchers working at the U.S. Department of Energy says it has created a kind of plastic that could lead to products that are 100 percent recyclable. The team recently reported the discovery in a study in the journal Nature Chemistry. The researchers say the new material is a plastic polymer(聚合物)called polydiketoenamine, or PDK. The team reports that the material can be broken down in parts at the molecular(分子)level. It can then be built up again to form plastics of different shapes, textures, colors and more. The researchers say this process can be repeated over and over again—without the plastic material losing any performance or quality.

Brett Helms is a scientist who worked on the study. He said, "Then we would be able to more effectively divert(转移)plastic from landfills and the oceans." "This is an exciting time to start thinking about how to design both materials and recycling facilities to enable circular plastics," he added.

1. What is the feature of plastic according to Paragraph1?

A．Light and cold.	B．Easy to break down.
C．Firm and changeable.	D．Colorful and endurable.

2. What do we know about plastic products?

A．Few are highly recycled.	B．They have quality problems.
C．They are environmentally friendly.	D．The process of recycling is cheap.

3. What is Helms'attitude to the new plastic?

A．Doubtful.	B．Optimistic.
C．Indifferent.	D．Negative.

4. Where does the text probably come from?

A．A science fiction.	B．A research plan.
C．A medical report.	D．A science magazine.

【推荐1】Peter, 60, loved his job as a bus driver. He had been one almost all his life, loving the company of the little children who rode his bus daily. It made him feel younger and more energetic. His record was clean, without one accident during his duty, which made him a trustworthy driver.

However, Mr. Clark, Peter’s boss, was concerned and thought that it was time for him to retire. “You don’t have a choice here, Peter,” he said seriously. “We don’t want to invite any risk to the children who take your bus every day. We need a replacement at this stage.”

“But I have a perfect record,”argued Peter. “You know, for an elderly man like me, my job is the only thing that keeps me alive. I want to keep my job.”

“Would you take responsibility if something bad happened to those children?” Mr. Clark said.

Peter thought it over, and very reluctantly, he gave in to Mr. Clark’s request. Peter decided to retire a week later.

His retirement day approached pretty soon. The day before his last day, Peter was dropping off the kids at his first stop when he looked out of the window and saw a lady on the road who had fainted (昏厥). He asked the kids not to leave the bus and got off to help the woman.

Just when he finished, he heard screams behind him. The children were looking out of the window and screaming. “Fire! Fire! Help!” “How could that have happened?” Peter was shaking in fear. With trembling hands, Peter dialed 911 and rushed to help the children. Peter covered himself with his jacket and burst into the flaming bus. He took the children out of the burning bus one by one. Thankfully, the firefighters arrived soon and helped Peter, saving all students.

The next day, Peter saw the entire school gathered in front of his home. When Peter approached them, Mr. Clark started clapping and everyone joined him. “You are a hero, Peter! You saved the lives of those young children,” he said. “You are the best driver. We hope you can keep the job!”

1. What made Mr. Clark concerned?

A．He couldn’t persuade Peter to retire.

B．Taking school bus was unsafe for children.

C．Peter was too old to be a school bus driver.

D．The school bus driver must be changed regularly.

2. What does the underlined “reluctantly” mean in Paragraph 5?

A．Angrily.	B．Carefully.
C．Doubtfully.	D．Unwillingly.

3. Why were the children screaming?

A．They were caught in the burning bus.	B．They were frightened by the woman.
C．They couldn’t find Peter on the bus.	D．They didn’t want a new school bus driver.

4. Which of the following is a suitable title for the text?

A．Putting out the fire	B．An old hero driver
C．Working after retirement	D．Dangerous journey on school bus

【推荐2】There’re always some stories in life that can hardly be forgotten and will restore our hope for holidays every time we recollect (回忆起).

Johnny and I, along with our two young sons, Barry and Doyle, lived in a village in southern Alabama in 1979. We had bought the boys a bicycle for the New Year, and had hidden it in the garage, where Johnny would assemble (组装) it on New Year’s Eve after the kids fell asleep. But that day, Johnny had to go to Brookley Air Force Base in Mobile, an hour away, to repair a jet. I had my hands busy with baking, preparing for holiday dinner and caring for two energetic boys.

Just as I was making the chocolate cake, a neighbor knocked on the door. Beatrice was the only person on our road with a telephone. The base had called to say that a heavy tool had come apart suddenly, hitting Johnny’s arm and breaking the bone. My brother Oto took me to the base hospital while my mother stayed with the children.

We got there to find Johnny with a cast on his arm, anxious to get home regardless of the doctor’s orders. It was New Year’s Eve, Johnny argued, and he had the bike to assemble for his boys. The doctor said he’d consider dismissing him the next morning if Johnny could find someone to drive him home. On New Year’s morning, Johnny called the base and was told everyone was off duty; there was no one to drive him home. Then he tried the motor pool. They said orders would have to come from someone higher up, so Johnny kept making calls. At last, a big blue car with the Air Force sign rolled up.

I was putting dinner on the table when hearing the car. We were thrilled to see Johnny assisted by a uniformed Air Force officer. With Otto’s help, Johnny assembled the boys’ gift, and they all had a good time that afternoon. Our hearts were full of gratitude to the people who had gone the extra mile to bring us together.

1. What had Johnny planned to do on New Year’s Eve?

A．Repair a jet.	B．Prepare a surprise gift.
C．Buy his sons a bike.	D．Assemble a bike with his sons.

2. Why did Beatrice come to the author’s house?

A．To relay a message.	B．To lend out her telephone.
C．To make a phone call.	D．To take the author to the hospital.

3. How can we describe Johnny?

A．Hardworking.

B．Stubborn.

C．Supportive.

D．Affectionate.

4. What can serve as the title for the text?

A．An Unexpected New Year Dinner	B．A Hard-Won New Year Present
C．A Treasured New Year Memory	D．A Life-Changing New Year Experience

【推荐3】Once upon a time, there was a beautiful bird, which was very curious about hell. When she was little, her mother always told her that if she didn’t master the flying skills, she would go to hell. She was so curious about hell that she always asked others what hell looked like, but no one was sure, because none of them had ever been there. Some said hell was a place full of water, and others told her that hell was full of burning fire. However, the bird knew they were lying. She wanted to find out what hell was.
When other birds were learning flying skills, she always hid herself and watched them. She thought in this way she could go to hell and see what hell looked like. However, she spent so little time learning flying skills that one day she was caught by a little boy. The little boy gave her to his grandpa in the countryside as a gift. The old man liked her very much. He made a delicate cage and put her in it. The bird was very worried because she thought she couldn’t find out what hell was like staying in this small cage. However, she couldn’t escape. Day after day, she just stayed in the cage, watching other birds flying. She lost her freedom and she became sadder and sadder. At last, she became ill. The old man finally opened the cage, but she was too weak to fly. Lying no the ground, she thought of the question that she ever asked all the time.
“What does hell look like?”
“Hell is a small well-decorated cage.” Before she closed her eyes forever, she finally answered that question herself.
1. What does the underlined word “master” in the first paragraph mean?

A．Miss.

B．Finish.

C．Follow.

D．Learn well.

2. Why did the bird hide herself when other birds were learning flying skills?

A．Because she was lazy.

B．Because she didn’t like learning flying skills.

C．Because she thought she could go to hell by doing this.

D．Because she thought she didn’t have to learn flying skills.

3. According to the passage, the bird at last found that     .

A．hell was a place full of water.	B．hell was a place full of burning fire
C．there was no hell	D．hell was a small well-decorated cage

【推荐1】Summer camp programs at Washington museums

Washington has a wide variety of museums. Many of these world-class museums has special programs for children. The following museums take this a step further and offer summer camp programs to educate and entertain kids during the summer months. Apply early because these camps can fill up fast.

National Building Museum-Artful Architecture Summer Camp.

July5-August12,2018.Ages 8-11.One-and two-week sessions. Campers can enjoy design challenges, field trips and more while experiencing architecture and design.(202)272-2448.

Tudor Place-Georgetown Summer History Weeks.

2018 dates to be announced. Ages4-10.Nine am-noon. Children experience a wide variety of indoor and outdoor activities that bring 175 years of American history to life and teach about natural environment. Children help prepare snacks and drinks of times past, try on period clothing, explore the historic garden, plant their own garden, play historic games, paint water-color landscapes, and much more.(202) 965-0400.

National Archives-Genealogy Camp.

2018 dates to be announced. Ages 12-and-up.Ever wondered about your family’s roots and who is on your family tree? This hands-on weeklong camp will introduce the basics of genealogy research. Discover how to use the resources of the National Archives to look into your past.(202)337-2288.

International Spy Museum -Spy Camp

August 1-5 and 8-12,2018,9 am-3 pm. Spy Camp is designed for ages 10 to13 and filled with top secret activities that will put spy skills to the test. Participants will learn from real spies, and hit the streets to run training missions. Develop a disguise for cover, make and break codes, develop escape techniques, create and use spy gadgets(装置)，discover the science behind spying, and more.(202)654-0930.

1. What can be concluded about these summer camp programs?

A．It is advised to sign up early for the programs.

B．They all provide outdoor activities.

C．They last for one and two weeks.

D．Participants should be more than 8 years old.

2. Those who want to learn about their family history at a camp should call_______ for further information.

A．(202)272-2448.	B．(202)337-2288
C．(202)965-0400	D．(202)654-0930

3. A child interested in escape skills should join _______.

A．Artful Architecture Summer Camp.	B．Georgetown Summer History Weeks.
C．Spy Camp.	D．Genealogy Camp.

【推荐2】Exploring a stadium is interesting. Without a game to focus on, you can actually appreciate the size and design of these places.

Raymond James Stadium

It offers a 75-minute tour showing visitors the inner workings of the Tampa Bay Buccaneers’ home stadium and the field. The stadium store has over 2,000 items. Tours run Mondays through Thursdays. Advance reservations are not required, but because tours may be cancelled, visitors should call (813)350-6500 to confirm a tour is running that day.

Tropicana Field

It offers 90-minute tours on weekdays. Some restricted areas that tour groups visit are the press box and the stadium control room. Guides will point out the stadium’s unique features and the team's history. Occasionally, groups will even see a player rehabbing (康复) or leave their jobs. Tour days vary, so call (813)326-7297 for an updated schedule.

Amalie Arena (圆形运动场)

It offers a behind-the-scenes tour on all Tampa Bay Lighting game days, starting 3.5 hours before the game and lasting an hour. Visitors see every floor of the arena. Tickets to that day’s game are not required. Buy tickets at the Amalie Arena ticket office or through the Tampa Bay Lightning app by clicking “experience”. For more information, call (813)301-6500.

Al Lang Stadium

The 70-minute tour is appropriate for all ages. No footballs, large bags, backpacks, cameras longer than 12 inches or video cameras are permitted on the tour. Please note there is no food available to purchase on site during the tour. All bags need to be searched upon arrival. Call (813)455-4921 to check tour availability on the day you plan to come.

1. Why should visitors call Raymond James Stadium ahead of time?

A．To book the ticket to it.

B．To know its inner workings.

C．To check if the tour is available.

D．To choose the place of it to visit.

2. Which place offers the longest tour?

A．Raymond James Stadium.

B．Tropicana Field.

C．Amalie Arena.

D．Al Lang Stadium.

3. Where can you read this text?

A．In a fashion magazine.

B．In a scientific journal.

C．In a travel brochure.

D．In a sports report.

【推荐3】While bees hopping from one flower to another is vivid to watch, having bees disturbing a backyard barbecue certainly isn’t. They may seem like pesky creatures to get rid of, but there are quite a few things you may not know about bees, especially the impact they have on our livelihood.

The main purpose of bees, particularly honey bees, is to help pollinate the plants around them. According to the Department of Entomology at Pennsylvania State University, pollinators (such as bees) help to fertilize plants, which results in “the formation of seeds and the fruit surrounding seeds”. Pollinators are necessary for three-quarters of our major food crops, including fruits, vegetables, and nuts. An estimated 300,000 species of plants need pollinators. That’s around 80 to 95 percent of plant species. Without pollinators, the number of crops we have will take a serious hit.

Other pollinators can help out with this process including butterflies, beetles, and flies. Even some birds and bats can be pollinators. However, bees of various species are known for being natural pollinators for plants.

Unfortunately, for years there has been an alarming decline of bees around the globe. The University of Vermont published a study stating that 23 percent of the wild bee population declined between 2008 and 2013. 139 counties in parts of California, the Pacific Northwest, the Midwest, west Texas and the Mississippi River valley have taken the worst hit in wild bee declines. Since 39 percent of U.S. croplands rely on pollinators for their crop including those beloved apple orchards and pumpkin patches in the fall, we are facing a serious threat.

By taking care of the bees, our world is able to benefit in terms of agricultural income and nutritious food supply. You may not be able to make a huge change on an industrial level, but as someone with a landscape of your own, why not help save the bees?

1. What is the best title for the passage?

A．Bees Is Disappearing?

B．How You Can Save Bees?

C．How Bees Help Pollinate the Plants?

D．Why You Shouldn’t Kill Bees in Your Yard?

2. What is the main purpose of bees?

A．To provide delicious honey.

B．To disturb backyard barbecue.

C．To get rid of some pesky creatures.

D．To help pollinate the plants around them.

3. Why does the author list the numbers in Paragraph 2?

A．To show the diversity of plant species.

B．To show how we depend on plants.

C．To prove the importance of pollinators such as bees.

D．To make a comparison between plants which need pollinators and which don’t.

4. Why does the author say “we are facing a serious threat”?

A．Because the bee population has decreased sharply.

B．Because lots of wild bees have been hit by people.

C．Because many people are attacked by wild bees.

D．Because the croplands have produced less crops in the fall.