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If you’re looking to buy a gift for your children, why not keep up with the trend and get the best hoverboard?
What is a Hoverboard?
A hoverboard is a two-wheeled personal transportation device. It’s electrical, portable and became highly popular in 2015 in reference to a popular 1980’s movie. Typically, this self-balancing device operates like a powered skateboard.
How Does a Hoverboard Work?
The device may have many designs, but the mechanism itself isn’t complicated. Basically, a standard hoverboard contains:
•Battery: stores the electrical power. Almost all hoverboards use a high-watt lithium-ion battery.
•Gyroscope (one for each wheel): allows riders to tilt (倾斜) the hoverboard while maintaining balance and adjusting their direction.
•Motor (one in each wheel): provides the power to the wheels to keep the rider balanced and upright.
•Logic board: functions as the hoverboard brain. It processes data — your speed, tilt, etc. — and sends information to the motors. This unit controls the power of the board so riders can adjust their speed.
All the above components work together to control the power and tilt of the hoverboards so the rider is balanced, upright and moving at a controlled speed.
Why Buy a Hoverboard?
Undoubtedly, hoverboards are cool. You’ve probably seen kids riding one around the house. They’re a phenomenon and everybody wants in. So, why deny your kids and prevent them from being part of this trend?
Where is a hoverboard legal?
Despite their wild popularity, hoverboards have yet to become “street-legal”. Currently, some places prohibit anyone under 16 from using these devices, and hoverboards are banned in academic institutions and public places, like campus buildings, parks, shopping malls and subway stations. Some places have also put speed limits on the devices and restricted their use to bike paths. However, open areas — including your yard — are free of these restrictions.
1.The logic board of a hoverboard can ______.
A.store electricity
B.power the wheels
C.send information to the riders
D.receive data and give command
2.According to the passage, a hoverboard can be used ______.
A.on campus B.in parks
C.on bike paths D.in shopping malls
3.What is the main purpose of this passage?
A.To evaluate a gift’s quality.
B.To recommend a gift choice.
C.To compare new hoverboard models.
D.To clarify functions of the latest hoverboards.
难度: 中等查看答案及解析
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Growing up, Deka Ismail says she let labels define what she could be. “I was a black girl, from a refugee (难民) family,” Deka said. “It was as if I was only allowed to explore in this predetermined box.”
After a high school chemistry class inspired her to think about a career in science and gave her confidence in the field, Deka learned to live outside labels and began making big plans for her future. Now she is about to begin her freshman year at the University of California, planning to become a professor.
Born and raised in San Diego’s City Heights neighbourhood, Deka is the daughter of a Somali refugee couple. While some might say Deka’s success happened in spite of her background, she would say differently, that her experiences shaped her and inspired her to be the driven, young scientist that she is today.
When Deka was eight years old, her mother got a job by studying hard back in school in order to support the whole family. That made Deka realize that education could make a difference to one’s life. She spent a lot of time in the library reading books, and didn’t do many of the things her peers did, like partying or having romantic relationships.
“I always felt like I had to be the perfect girl for my family,” Deka said. “You have to not even do your best but two times better than everyone else. I felt like the whole world was waiting for me to mess up.”
Deka’s efforts paid off. The summer before her senior year of high school, she was accepted to the American Chemical Society Project SEED Programme. “She brought both enthusiasm and focus,” Botham, a researcher at this research institute, recalled. “She arrived every day ready to work, ready to learn and ready to tackle new challenges regardless of whether or not she had done anything similar.”
When asked what advice she would give to others like her, Deka warned them not to underestimate themselves. “Don’t tell yourself that scholarship is too big or this programme is too competitive or I’ll never get into this school, ” she said. “I was not sure whether I could make it until I started seeing the acceptance letters rolling in.”
1.From the passage, we can learn that ______.
A.Deka was adopted by a refugee family
B.Deka spent a lot of time going to parties
C.Deka became a professor after graduation
D.Deka’s experiences drove her to work hard
2.Deka realized the importance of education ______.
A.from her mother’s experience B.after her chemistry class
C.by reading books in the library D.through working at the institute
3.According to the last paragraph, Deka advised that students be ______.
A.patient B.confident
C.ambitious D.generous
4.What does the story intend to tell us?
A.Life is not all roses.
B.Practice makes perfect.
C.Well begun is half done.
D.Hard work leads to success.
难度: 中等查看答案及解析
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A group of blue-faced birds step through the grass shoulder to shoulder, red eyes looking around. They look like middle schoolers seeking a cafeteria table at lunchtime. Perhaps they’re not so different.
A new study, led by Damien Farine, an ornithologist who studies collective behaviour, shows that the vulturine guineafowl of eastern Africa, like humans, have multilevel societies. In the past, scientists assumed such social structures required a lot of brainpower. But the pea-brained guineafowl are revealing the faults in that assumption.
These large birds wander across the landscape in packs, often walking so closely that their bodies touch. They may fight each other to maintain their strict hierarchies (等级制度), but at other times they engage in friendly behaviours like sharing food.
Suspecting the guineafowl might have a social structure, Dr. Farine and his colleagues began a thorough study of their society. For a whole year, they made daily observations of 441 birds. Coloured leg bands in unique combinations let researchers tell the black-and-blue birds apart. They also attached GPS devices to the backs of 58 birds, which let them see exactly where every group went, 24 hours a day.
The findings of the research suggest that the vulturine guineafowl have a multilevel society. There are groups within groups within the population as a whole. There even seem to be groups of friends within the small groups. This is the first time anyone has observed such a society in a bird.
And Dr. Farine emphasizes this particular bird’s tiny brain size: “They don’t only have small brains relative to mammals (哺乳动物), they also have quite small brains relative to other birds,” he said.
According to him, living in this kind of society might actually make it easier to keep track of the social order. For example, if groups are stable and a bird can identify just one or two individuals within a group, it knows which group it’s looking at — no need for a brain that can recognize every single animal. Multilevel societies also let animals adjust their group sizes based on whatever challenges they’re facing. Depending on what enemies or resources are around, it might make sense to travel in a combined group rather than a smaller one.
“Having a multilevel structure may not require having a large brain,” Dr. Farine said. There may be more birds and other animals out there that, although small-brained, have societies as many-leveled as our own.
1.According to the passage, what inspired Dr. Farine to carry out the study?
A.The guineafowl’s social behaviour.
B.Previous assumptions about birds.
C.His interest in animal brainpower.
D.The faults in earlier research.
2.What is Paragraph 4 mainly about?
A.The research subjects. B.The research methods.
C.The research findings. D.The research equipment.
3.What can be learned from the passage?
A.Complex social systems can be a disadvantage to the guineafowl.
B.The guineafowl are good at recognizing individuals in a group.
C.Birds maintain social order by travelling in combined groups.
D.Small-brained animals can form multilevel societies.
4.What is the main purpose of the passage?
A.To present the findings of a study of the guineafowl.
B.To explain the interaction patterns in multilevel societies.
C.To introduce a new approach to observing the guineafowl.
D.To uncover clues about how complex societies are formed.
难度: 中等查看答案及解析
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For several decades, there has been an extensive and organized campaign intended to generate distrust in science, funded by those whose interests and ideologies are threatened by the findings of modern science. In response, scientists have tended to stress the success of science. After all, scientists have been right about most things.
Stressing successes isn’t wrong, but for many people it’s not persuasive. An alternative answer to the question “Why trust science?” is that scientists use the so-called scientific method. If you’ve got a high school science textbook lying around, you’ll probably find that answer in it. But what is typically thought to be the scientific method — develop a hypothesis (假设), then design an experiment to test it — isn’t what scientists actually do. Science is dynamic: new methods get invented; old ones get abandoned; and sometimes, scientists can be found doing many different things.
If there is no identifiable scientific method, then what is the reason for trust in science? The answer is how those claims are evaluated. The common element in modern science, regardless of the specific field or the particular methods being used, is the strict scrutiny (审查) of claims. It’s this tough, sustained process that works to make sure faulty claims are rejected. A scientific claim is never accepted as true until it has gone through a lengthy “peer review” because the reviewers are experts in the same field who have both the right and the obligation (责任) to find faults.
A key aspect of scientific judgment is that it is done collectively. No claim gets accepted until it has been vetted by dozens, if not hundreds, of heads. In areas that have been contested, like climate science and vaccine safety, it’s thousands. This is why we are generally justified in not worrying too much if a single scientist, even a very famous one, disagrees with the claim. And this is why diversity in science — the more people looking at a claim from different angles — is important.
Does this process ever go wrong? Of course. Scientists are humans. There is always the possibility of revising a claim on the basis of new evidence. Some people argue that we should not trust science because scientists are “always changing their minds.” While examples of truly settled science being overturned are far fewer than is sometimes claimed, they do exist. But the beauty of this scientific process is that it explains what might otherwise appear paradoxical (矛盾的): that science produces both novelty and stability. Scientists do change their minds in the face of new evidence, but this is a strength of science, not a weakness.
1.How does the author think of the scientific method?
A.Stable. B.Persuasive.
C.Unreliable. D.Unrealistic.
2.What does the underlined word “vetted” in Paragraph 4 probably mean?
A.Explained. B.Examined.
C.Repeated. D.Released.
3.According to the passage, the author may agree that ______.
A.it is not persuasive to reject those faulty claims
B.settled science tends to be collectively overturned
C.a leading expert cannot play a decisive role in a scrutiny
D.diversity in knowledge is the common element in science
4.Which of the following would be the best title for the passage?
A.Put Your Faith in Science B.Defend the Truth in Science
C.Apply Your Mind to Science D.Explore A Dynamic Way to Science
难度: 困难查看答案及解析