【推荐1】The Only Exercise You Need

To walk is to be human. We’re the only primate that gets around by standing up and putting one foot in front of the other. In more than 4 million years humanity’s ancestors have been bipedal.     1    

But walking is more than just transportation. It also happens to be really good for us. Countless scientific studies have found that this simple act can provide a number of health benefits and help people live longer.     2    

How much walking should one aim for? You’ve likely heard we need 10, 000 steps a day. That’s about 5 miles.     3     Instead, it stems from a 1960s advertising campaign to promote a pedometer in Japan. Perhaps because it’s a round number and easy to remember, it stuck.

Since the 1960s, researchers have studied the 10, 000-steps-a-day standard and have turned up mixed results. Although 10, 000 steps is certainly a healthy and worthwhile goal, it’s not a one-size-fits-all recommendation.

For instance, a recent Harvard University study involving more than 16, 000 senior women found that those who got at least 4, 400 steps a day greatly reduced their risk of dying prematurely when compared with less active women. The study also noted that these benefits continued up to 7, 500 steps before leveling off. This 7, 500 mark isn’t surprising:     4    

Research has shown that picking up the pace might be a good idea, too—fast enough to raise your heart rate, even if just for a short burst. The benefits of walking depend on frequency, intensity and duration. So walk often, walk fast and walk long.

A．Contrary to popular belief, this recommendation doesn’t come from science.

B．Without doubt, walking alone serves as the only activity for mankind to build up strong constitutions.

C．Our ability to walk upright has allowed humankind to travel great distances and survive changing climates, environments and landscapes.

D．It’s in line with common public health recommendations, such as the Centers for Disease Control and Prevention’s recommendation of 150 minutes of moderate physical activity a week for adults.

E．In fact, a walking routine — if done properly — might be the only aerobic exercise people need.

F．However, it never means that we should follow this recommendation as our standard for walking.

【推荐2】If you have trouble falling asleep, listen up. You might fall asleep 15 minutes earlier and wake up far less during the night if you put on a pair of socks at bedtime.

To understand why, you first need to grasp the relationship between core body temperature and sleep. During daylight hours, the human body has an average temperature of 37℃. But your core body temperature drops as much as 1.2℃ over one night's sleep. This gradual decrease is a key part of how we sleep. Put simply, the faster you can lower your core body temperature, the faster you will fall asleep.

One way that your body controls its temperature is through blood vessels (血管) in the skin. If your body is too hot, your blood vessels widen, pushing the warmer blood nearer the skin's surface, helping it to cool. If your body is too cold, the opposite happens. Your blood vessels narrow, restricting the flow of blood to the surface.

The palms of your feet are one of your body's most efficient heat exchangers, since they are hairless and less protected than other skin surfaces. Researchers have shown that warming the feet before going to sleep using a warm foot bath or by wearing socks promotes blood vessel widening, which in turn lowers the body's core temperature faster than going to sleep with cold, bare feet.

       Scientists suspect that socked feet have a sleep-benefiting effect on the brain as well. The warm-sensitive neurons (神经元) in the brain become more active when there's a temperature difference between the body's core and the feet. Researchers have found that these neurons become more active as we get sleepy and slow down as we wake up, so that warming up the feet before bedtime may give them an extra drive, making you feel sleepier.

In a small study, researchers found that wearing a pair of special “sleeping socks” not only sped up the coming of sleep, but increased overall sleep time by an average of 30 minutes and cut nighttime waking episodes in half. If you're worried about becoming too warm, look for socks made of natural fibers.

1. In which section of a newspaper can we find this text?

A．Lifestyle.

B．Trend.

C．Opinion.

D．Advertisement.

2. What change does warm feet bring to the body?

A．Slowed brain reaction.	B．Narrowed blood vessels.
C．Decreased blood pressure.	D．Reduced core body temperature.

3. How might the brain's warm-sensitive neurons help sleep?

A．To help to warm up the feet.	B．To speed up temperature growth.
C．To bring on sleepiness when activated.	D．To slow down the brain's blood flow.

4. What is the finding of the small study mentioned in the last paragraph?

A．The warmth of socks depends on their material.

B．People wearing socks fall asleep 50 percent faster.

C．Special socks increase temperature more effectively.

D．Sock wearing helps people sleep longer and wake less.

【推荐1】There are many programs for high school students today that help lonely teenagers deal with loneliness. However, loneliness is not only an issue for teens but also an important and rarely acknowledged one in the elderly.

In Britain, Tracey Crouch was appointed to be the first Minister of Loneliness in order to address the issues caused by loneliness. This is the first time such a position has been created.

In Britain, there are around 9 million people who say they are lonely frequently. In Germany, a study conducted by Ruhr University Bochum found that 20 percent of people over the age of 85 felt lonely, and 14 percent of those between age 45 and 65 felt socially lonely. In the United States, more than 25 percent of the population lives alone, more than 50 percent are unmarried.

Loneliness is generally associated with heart disease, overweight, and anxiety. Additionally, the stress from loneliness can cause your cells to change on a molecular(分子)level that reduces its abilities to defend your body against diseases. In fact, doctors believe having feelings of loneliness is equivalent to smoking 15 cigarettes per day in regard to its effect on health!

In Britain, the new Minister of Loneliness will help introduce government policies on the issue and fund a charity—an organization for helping people in need, to devote their efforts towards aiding loneliness. There are charities that link lonely seniors to high school students in order to give them a line of communication whenever they feel lonely!

The possibilities for the new Minister of Loneliness are endless. For example, she can provide education services to household businesses so that they can identify lonely customers if they see one. Loneliness fits into the category of being a social issue that must be monitored by the entire community in order to help those in need. Therefore, government involvement in medical services and care for seniors and others is vital for happy seniors.

1. How does the author develop Paragraph 3?

A．By listing some statistics.

B．By giving examples of lonely people.

C．By pointing out similarities and differences.

D．By comparing different cultures in different countries.

2. What does the underlined word “equivalent” in Paragraph 4 probably mean?

A．Relevant.	B．Similar.
C．Opposite.	D．Superior.

3. What will the Minister of Loneliness do?

A．Do housework for lonely people.

B．Develop friendships with the elderly.

C．Help fund charities to aid lonely people.

D．Communicate with anxious school students.

4. What is the main idea of the text?

A．UK becomes the capital of loneliness.	B．Loneliness affects old people’s life worldwide.
C．Many teenagers suffer from loneliness.	D．UK’s Minister of Loneliness settles loneliness.

【推荐2】“Confidence” is probably one of the most noticeable traits (品质) in the Americans. They show confidence in the way they talk, the way they smile, the way they dress and the way they walk. Living and competing with all these confident American students, I find it extremely important to be confident as an international student and instructor. As a student, being confident means you should never hesitate to raise your hand whenever a question or a point comes to your mind. Don't mind if it sounds simple or silly. Otherwise you will never get a chance to speak in class at all. What's worse, the professors may think you are not prepared for the discussion or you do not have your own opinion on the issue—this is the last comment any graduate would like to receive.
Being confident for me as a foreign instructor means calmly asking the student to repeat what he or she has said if I did not get it. Pretending to understand what you actually did not may just bring yourself embarrassment or even disgrace. But the time I most need to be confident is when my students come to my office and bargain about the grades I have given for their speeches. (The course I'm teaching here is Public speaking). Modesty is a trait highly valued in China, but it won't be of much help here if you want to survive and succeed in a good American graduate program.
1. To compete with American students it's very important to     .

A．be quite confident

B．be polite and friendly

C．have more discussions with them

D．understand what they think about

2. A professor will have the worst opinion of a student who     .

A．gives a silly or simple answer

B．tries to seize any chance to speak in class

C．shows no interest in the course

D．is considered to have no opinion of his own

3. The author is most likely to feel embarrassed if       .

A．he asks a student to repeat what he has said

B．the students bargain with him

C．he pretends to know what he doesn't

D．he has to give a speech

4. We learn from the second paragraph that       .

A．we should also remain modest in America

B．modesty doesn't help you much in America

C．Americans also like modest people

D．modesty can help you through an American graduate program

5. What can we infer from the passage?

A．American students are ready to accept the grades from the teacher.

B．The writer teaches in Europe for a living.

C．Students are encouraged to present simple questions.

D．One’s ignorance will give away in time.

【推荐3】One day, gardeners might not just hear the buzz of bees among their flowers, but the whirr of robots, too. Scientists have managed to turn an unassuming drone (无人机) into a remote-controlled pollinator (授粉媒介) by attaching horsehairs coated with a special, sticky gel to its underbelly.

Animal pollinators are needed for the reproduction of 90% of flowering plants and one third of human food crops. Chief among those are bees — but many bee populations in the United States have been in steep decline in recent decades. Thus, the decline of bees isn't just worrisome because it could disrupt ecosystems, but also because it could disrupt agriculture and economy. People have been trying to come up with replacement techniques, but none of them are especially effective yet.

Scientists have thought about using drones, but they haven't figured out how to make free-flying robot insects that can rely on their own power source without being attached to a wire. “It’s very tough work,” said senior author Eijiro Miyako, a chemist at the National Institute of Advanced Industrial Science and Technology. His particular contribution to the field involves a gel, one he’d considered a mistake 10 years before and stuck in a storage cabinet. When it was rediscovered a decade later, it hadn’t dried up or degraded at all. “I was so surprised because it still had high viscosity,” Miyako said.

The chemist noticed that when dropped, the gel absorbed an impressive amount of dust from the floor. Miyako realized this material could be very useful for picking up pollen (花粉). He and his colleagues chose a drone and attached horsehairs to its smooth surface to mimic a bee’s fuzzy body. They coated those horsehairs in the gel, and then controlled the drones over lilies, where they would pick up the pollen from one flower and then deposit the pollen at another one, thus fertilizing it.

The scientists looked at the hairs under a scanning electron microscope and counted up the pollen grains attached to the surface and found that the drones whose horsehairs had been coated with the gel had about 10 times more pollen than those that had not been coated with the gel.

Miyako does not think such drones would replace bees altogether, but could simply help bees with their pollinating duties. There’s a lot of work to be done before that's a reality, however. Small drones will need to become more controllable and energy efficient, as well as smarter, with better GPS and artificial intelligence.

1. What does the underlined word “viscosity” in Para.3 probably mean?

A．Hardness.	B．Stickiness.
C．Flexibility.	D．Purity.

2. We can learn from the passage that ______.

A．bees disrupt both agriculture and economy

B．scientists have invented self-powered robot insects

C．bees in the United States are on the edge of extinction

D．Miyako found the special feature of the gel by chance

3. A drone works best in picking up pollen when ______.

A．its body is made like a bee’s

B．its GPS works more efficiently

C．some flowers are coated with the gel

D．horsehairs with the gel are attached to it

4. According to Eijiro Miyako, the drones ______.

A．are not yet ready for practical use

B．may eventually replace bees in the future

C．are much more efficient than bee pollinators

D．can provide a solution to economic depression

【推荐1】Population and climate

The human population on Earth has grown to the point that it is having an effect on Earth’s atmosphere and ecosystems. Burning of fossil fuels, deforestation, urbanization, and cultivation of rice and cattle are increasing the concentration of carbon dioxide, nitrogen oxides and dust in the atmosphere. About 70 percent of the Sun’s energy passes through the atmosphere and strikes Earth’s surface. This radiation heats the surface of the land and ocean, and these surfaces then reradiate infrared radiation back into space. This allows Earth to avoid heating up too much. However, not all of the infrared radiation makes it into space; some is absorbed by gases in the atmosphere and is reradiated back to Earth’s surface. A greenhouse gas is one that absorbs infrared radiation and then reradiates some of this radiation back to Earth. Carbon dioxide and nitrogen oxides are greenhouse gases. In fact, without greenhouse gases in the atmosphere, scientists calculate that Earth would be about 33℃ cooler than it currently is.

The current concentration of carbon dioxide in the atmosphere is about 360 parts per million. Human activities are having a major influence on atmospheric carbon dioxide concentrations, which are rising so fast that current predictions made by scientists are that atmospheric concentrations of carbon dioxide will double in the next 50 to 100 years.

Some scientists predict that a doubling of carbon dioxide concentration will raise global temperatures anywhere between 1.4℃ and 4.5℃. The increase in temperature will not be uniform, with the smallest changes at the equator and changes two or three times as great at the poles. The local effects of these global changes are difficult to predict, but it is generally agreed that they may include alterations in ocean currents, increased winter flooding in some areas of the Northern Hemisphere, a higher incidence of summer drought in some areas, and rising sea levels, which may flood low-lying countries.

1. It can be inferred from the passage that one positive aspect of greenhouse gases is that they _______.

A．remove pollutants from Earth’s atmosphere and ecosystems

B．absorb 70 percent of the Sun’s energy

C．help keep Earth warm

D．double atmospheric concentrations of carbon dioxide

2. Which of the sentences below BEST summarizes the highlighted sentence?

A．The rapid rise of atmospheric carbon dioxide concentrations is mostly caused by human activities.

B．Human activities will no longer have an influence on atmospheric carbon dioxide concentrations in the next 50 to 100 years.

C．Some scientists predict that atmospheric carbon dioxide concentrations will not increase in the next 50 to 100 years.

D．Some scientists recently predict that atmospheric carbon dioxide concentrations that are largely influenced by human activities will double in the next 50 to 100 years.

3. The word “uniform” in paragraph 3 is closest in meaning to _______.

A．different

B．identical

C．comparable

D．changeable

4. What are the local effects of global changes?

A．Sea levels will fall.

B．The effects will not occur in some regions of the world.

C．The local plants and forests will be permanently damaged.

D．It is hard to know exactly what form the local effects will take.

5. Which of the following statements is NOT true?

A．Raising livestock and growing rice are the actions of humans.

B．The surface of the land and ocean can help decrease the temperature of Earth.

C．Although carbon dioxide concentration may double in the future, temperatures at the North Pole and South Pole may not change.

D．Nitrogen oxides absorb infrared radiation that can increase the temperature of Earth.

【推荐2】By analyzing the movement of the smile across a person’s face, the software developed by researchers at the University of Bradford can determine whether or not the expression is true. The most significant movements detected by the software were around the eyes, supporting popular theories that a true smile is one that can be seen in a person’s eyes.

“A smile is perhaps the most common of facial expressions and is a powerful way of signaling positive emotions (情绪)” says Hassan Ugail, Professor of Visual Computing at the University of Bradford, who led the research. “Techniques for analyzing human facial expressions have advanced a lot in recent years but distinguishing between true and false smiles remains a challenge because humans are not good at picking up the relevant messages.”

The software works by first mapping a person's face from within a video recording, and identifying the mouth, cheeks and eyes of the subject. It then measures how they move through the progress of the smile and calculates the differences in movement between the video pieces showing true and false smiles. They found significant differences in the way the subjects' mouths and cheeks moved when comparing the true and the false expressions. The movements around the subjects’ eyes, however, showed the most striking difference, with true smiles producing at least 10 percent more movement in these muscles (肌肉).

“We use two main sets of muscles when we smile — the zygomaticus major, which is responsible for the movements upwards of the mouth and the orbicularis oculi which causes movements around our eyes,” explains Professor Ugail. In false smiles it is often only the mouth muscles that move but, as humans we often don’t spot the lack of movement around the eyes.

He adds, “An objective way of analyzing whether or not a smile is true could help us develop improved interactions (互动) between computers and humans. It could also be important to scientists aiming to gain more understanding into human behavior and emotion.”

1. Why is it hard for humans to recognize a false smile?

A．Humans are good at hiding their smiles.

B．The relevant details are hard to catch for our eyes.

C．Humans often put on too many facial expressions.

D．Techniques for analyzing facial expressions are hard to develop.

2. What do the researchers find by the software?

A．People usually use two main sets of muscles when smiling.

B．True smiles produce more muscle movement around eyes.

C．Mouths and cheeks move the same for true and false smiles.

D．True smiles are a powerful way of signaling positive emotions.

3. What can we infer from Professor Hassan Ugail?

A．There are different sets of muscles on every human’s face.

B．The software can improve humans’ behavior and emotion.

C．Humans can spot the movement around the eyes in true smiles.

D．The interactions between computers and humans remain to be improved.

4. What is the best title for the text?

A．Eyes Can Smile

B．Smiles Can Show One's Personality

C．More Smiles, Longer lives

D．True Smiles, False Movements

【推荐3】阅读短文，按照题目要求用英语回答问题。

As a graduate student, my teacher taught me some unforgettable lessons. Once we were in Cardiac CathLab (心导管插入实验室), we had a middle-aged man around 50 years as our patient for angioplasty (血管成形术). But suddenly this patient fell down, blood pressure went down, heart rates went up, and couldn’t breathe. We had to put him on a ventilator (人工呼吸机) and start emergency drugs to keep his blood pressure normal. Nobody could understand what exactly happened, because the process went well. My teacher was calm all this time.

No rush, no shouting, no serious expressions on his face which could tell that he was stressed. I was bewildered! How could he be so calm? How could he handle things without any stress? Did he lose his pity for this man?

While I was filled with thoughts inside my head, he told me to tell the Cardiac surgeon that we got an emergency Cardiopulmonary bypass surgery (体外循环心脏手术). I couldn’t understand. Then one nurse told me that patient’s heart got a rent (裂缝) during the process, so we had to take him to the operation theatre immediately.

I can’t forget that day. I got to CathLab at 8 a.m. and came out of the operation theatre at 8 p.m. with the same patient. I asked my teacher, “How could you be so calm in such a situation?”

He said, “Day in and day out I have faced such things for the last 20 years. You should be calm because whatever diseases they have, you have to manage those. Patients’ lives are in your hands. Being frightened would increase the risk of the operation. You can’t afford to lose control because within seconds patients would be either dead or brain dead.

I have followed his instructions since then. And believe me it takes experience to keep your stress under control in such situations. I am still learning it; there is a long way to go.

1. What was wrong with the middle-aged man during the process of angioplasty? (no more than 15 words)
2. How do you understand the underlined part in Paragraph 2? (no more than 5 words)
3. Why did the patient need an emergency Cardiopulmonary bypass surgery immediately? (no more than 10 words)
4. How could the author’s teacher deal with emergency situations? (no more than 5 words)
5. What can you learn from the story? Please write it in your own words. (no more than 20 words)

【推荐1】As a historian who's always searching for the text or the image that makes us re-evaluate the past, I've become preoccupied with looking for photographs that show our Victorian ancestors smiling (what better way to shatter the image of 19th-century prudery?). I've found quite a few, and - since I started posting them on Twitter — they have been causing quite a stir. People have been surprised to see evidence that Victorians had fun and could, and did, laugh. They are noting that the Victorians suddenly seem to become more human as the hundred-or-so years that separate us fade away through our common experience of laughter.

Of course, I need to concede that my collection of ‘Smiling Victorians’ makes up only a tiny percentage of the vast catalogue of photographic portraiture created between 1840 and 1900, the majority of which show sitters posing miserably and stiffly in front of painted backdrops, or staring absently into the middle distance. How do we explain this trend?

During the 1840s and 1850s, in the early days of photography, exposure times were notoriously long: the daguerreotype photographic method (producing an image on a silvered copper plate) could take several minutes to complete,resulting in blurred images as sitters shifted position or adjusted their limbs. The thought of holding a fixed grin as the camera performed its magical duties was too much to contemplate, and so a non-committal blank stare became the norm.

But exposure times were much quicker by the 1 880s, and the introduction of the Box Brownie and other portable cameras meant that, though slow by today's digital standards, the exposure was almost instantaneous. Spontaneous smiles were relatively easy to capture by the 1890s, so we must look elsewhere for an explanation of why Victorians still hesitated to smile.

One explanation might be the loss of dignity displayed through a cheesy grin. “Nature gave us lips to conceal our teeth.” ran one popular Victorian maxim, alluding to the fact that before the birth of proper dentistry mouths were often in a shocking state of hygiene. A flashing set of healthy and clean, regular “pearly whites” was a rare sight in Victorian society, the preserve of the super- rich (and even then, dental hygiene was not guaranteed).

A toothy grin (especially when there were gaps or blackened gnashers) lacked class: drunks, tramps and music hall performers might gurn and grin with a smile as wide as Lewis Carroll's gum-exposing Cheshire Cat, but it was not a becoming look for properly bred persons. Even Mark Twain,a man who enjoyed a hearty laugh, said that when it came to photographic portraits there could be “nothing more damning than a silly, foolish smile fixed forever”.

1. According to paragraph 1, the author's posts on Twitter ________.

A．illustrated the development of Victorian photography.

B．highlighted social media's tole in Victorian researches.

C．re-evaluated the Victorian's notion of public image.

D．transformed people's initial cognition of the Victorians.

2. Mark Twain is quoted to show that the disapproval of smiles in pictures was ________.

A．a thought-provoking idea

B．a two-edged sword

C．a controversial view

D．a deep-rooted belief

3. Which of the following questions does the text answer?

A．When did the Victorians start to view photograph differently?

B．How come most Victorians looked stem and stiff in photographs?

C．How can re-assessing pasts reveal the contemporary tendency?

D．How did smiling in photograph become a post-Victorian norm?

【推荐2】On some Swedish trains, passengers carry their e-tickets in their hands—literally. About 3,000 Swedes have chosen to insert grain-of-rice-sized microchips beneath the skin between their thumbs and index fingers. The chips, which cost around $150, can hold personal details, credit-card numbers and medical records. They rely on Radio Frequency ID (RFID), a technology already used in payment cards, tickets and passports.

By one estimate there are 10,000 cyborgs with chip implants around the world. Sweden, home to several microchip companies, has the largest share. Fifty employees of Three Square Market, a Wisconsin-based firm, volunteered to receive chip implants that can be used to pay at vending machines and log in to computers.

Jowan Österlund, the founder of BioHax, a Swedish firm, claims chips are more secure than mobile phones because they are hard to hack. But skeptics still have concerns. RFID chips do not have GPS, but they leave a digital trail when they interact with doors, printers or turnstiles. In 2004 the Mexican attorney-general and his staff had chips inserted in their arms that tracked who had accessed sensitive information.

So why take the risk? Convenience is one draw. The infrastructure for microchip use exists wherever contactless IDs or payments are accepted. Sweden is well suited, as the world’s second most cashless country (after Canada). But the chips have little use unless companies play along. Few shops recognise chip implants yet. Even those organisations that do have had teething troubles. When Swedish rail officials began scanning passengers’ microchips, they saw LinkedIn profiles rather than evidence of ticket purchases. For now the chips are used largely as digital business cards, substitutes for keys or to store emergency documents such as wills.

So exhibitionism is another explanation. Chip enthusiasts include followers of a “trans-humanist” ideology that seeks to make full use of human bodies with technology. Elon Musk, an American entrepreneur, has invested in tech that merges machines with human brains. Some Christians, meanwhile, fear that microchips are “marks of the beast” foretold in the Bible. Hardly, says Mr Österlund. After all, “people once thought the Beatles were the Antichrist.”

1. With an inserted microchip, people can do the following except ________.

A．storing emergency documents in it	B．taking a train without a paper ticket
C．paying wherever they shop without cash	D．looking up their medical records from it

2. By mentioning the Beatles in the last paragraph, the author intends to ________.

A．prove there is no need to fear microchips

B．show they were once looked down upon

C．explain how people think about microchips

D．compare them with the popular microchips

3. What does the passage mainly talk about?

A．Different ways to have microchips inserted into human bodies.

B．Technology behind microchips being inserted into human bodies.

C．Great convenience inserted microchips bring to people in their daily life in Sweden.

D．Reasons why Sweden has the most people in the world to have microchips inserted.

【推荐3】Bumblebees(大黄蜂）aren't simply dancing around our gardens.Now,a new study suggests that bumblebees force plants to flower by making small bites in their leaves.

Consuelo De Moraes,a scientist at the Swiss Federal Institute of Technology in Zurich, noticed bumblebees making tiny bites in the leaves of their greenhouse plants.The insects didn't seem to be carrying off the bits of leaves to their nests or eating them.

Supposing the bees were causing the plants to flower,Consuelo De Moraes and his team set up a series of experiments.They placed flowerless tomato plants and two kinds of worker bees in cages.The bees fed with enough pollen(花粉）seldom damaged the plants,while the ones without having pollen for three days busily did so.Scientists then removed the plants after the bees made five to ten holes in their leaves.The small holes caused the tomato plants to flower a month sooner than usual.

＂In a sense,the bees are signaling,'Hey,we need food.Please speed up your flowering, and we'll pollinate(授粉）you."said Lars Chittka,a behavioral scientist at Queen Mary University of London.

To make sure that their discoveries didn't result from the man-made conditions in the lab, the scientists placed bumblebees and a variety of flowerless plant species on their Zurich rooftop in late March 2018.The bees were free to fly as far as they could.Yet they set to work damaging the leaves on all the non-flowering plants nearest to their nests.The bees lost interest in this activity toward the end of April as more flowers came out,according to the study.

The research is of great value,for it can increase the human food supply.However,some questions remain to be answered,like"Why do the bites cause the plants to flower?"and ＂Does flowering early lead to higher fitness for the plants?"

1. Why did the bumblebees bite the leaves?

A．Because they wanted to eat the leaves.

B．Because they were to get pollen to eat.

C．Because they were exercising to be stronger.

D．Because they would carry the leaves to the nests.

2. What does the underlined"this activity"in Paragraph 5 refer to?

A．Dancing on the leaves.

B．Flying as far as they could.

C．Making small holes in the leaves.

D．Damaging the flowers near their nests.

3. What's the possible benefit of the research?

A．Humans may produce more food.

B．Bumblebees can have more to eat.

C．Some plants can have more flowers.

D．Some plants will gain higher fitness.

4. What's the main idea of the passage?

A．Bumblebees speed up plants flowering by biting leaves.

B．Human food supply will largely depend on bumblebees.

C．Bumblebees like to damage the plants nearest their nests.

D．Rooftop plants flower more than the ones in greenhouses.