Scientists have long had it in their mind to make a robot lizard . They began with finding out why a lizard can hang on a wall. They noticed the lizard's toes were unique: They have suckers , which enable it to hang on walls. They, therefore, made a robot with suckers on its hands and feet. The robot could hang on the wall but fell off when crawling. So, they went on researching. 6 years ago, scientists discovered that suckers only were not enough. It is the bristles on each foot that adds friction and static adsorption that makes a lizard move on the smooth wall easily without falling down. Then scientists made great efforts to fix thick bristles to the robot's hands and feet. However, the effect was not satisfactory. The robot still couldn't attach itself firmly to the wall. Scientists got puzzled: How on earth can the lizard crawl on an extremely smooth wall or even on a ceiling without dropping off? An accidental finding inspired them: One day a scientist happened to see an animal attack a lizard and bite off its tail. The lizard broke away from the animal's teeth and threw itself on a wall to escape, only to fall off heavily on the ground. The scientist wondered: Is it the tail that plays an important role in its travelling on the wall? He caught some lizards for an experiment. The result proved his assumption: A tailless lizard has no trouble walking on an ordinary wall but can't on a smooth one. A further study showed the lizard's tail can prevent it falling over backward and, what's more, that the tail acts as an additional leg while one of the lizard's legs leaves the wall, which is always the case while it is walking on the wall. Thus, Tailbot, a super tailed robot, is born. The bristles function as something _ . A) to protect the lizard's toes from injury B) to produce friction and static adsorption C) to prevent a lizard falling over backward D) to help a lizard move about without falling
B
Over 60%of pupils in South African schools choose English for learning and teaching, but only 7%of pupils speak English as their home language, a recent South Africa survey shows. Out of the country's 12.2 million pupils only 851,536 speak English at home, yet 7.6 million pupils choose English as their favorite language of learning and teaching. Zulu is the most widely spoken home language, spoken by over 3.1 million pupils. However, less than a third of them choose to be taught in Zulu. The same thing is true of Pedi-speaking pupils, only a third of such pupils choosing to be taught in their home language. Besides English, Afrikaans is the only language that has more pupils choosing it as their language of instruction than it has pupils who speak it at home. In primary schools, most pupils will choose African languages. As early as grade four, many would choose English or Afrikaans in their lessons. The rising number of English-learning pupils is mainly caused by social and cultural reasons. English is the most common spoken language in official and public life in South Africa, the survey reports. In April 2011, the leaders of higher education and training said that they would take some steps to improve the university teaching and prevent the continuing _ of African languages. They suggested that in future every South African university student could be required to learn at least one African language in order to complete their studies at school. What is the survey in the passage mainly about? A) The use of native languages in South African families. B) The language choice and use among South African pupils. C) The progress in South Africa's language teaching education D) The spread of English at schools in South Africa.
B
Q: When one person gains weight, their close friends often follow. Researchers have just offered evidence in a study that says obesity appears to spread through society. But the findings might also offer hope. If friends help make obesity acceptable, then they might also be influential in losing the fat. The researchers note that support groups are already an effective tool in dealing with other socially influenced problems, like alcoholism . The findings appeared in the New England Journal of Medicine. The researchers used information collected from 12,000 people. It was collected between 1972 and 2003 as part of the Framingham Heart Study. The information was highly detailed. There was even contact information for close friends of the people in the study. The researchers examined more than 40,000 social ties. They found a person's chances of becoming severely overweight increased by 50% if a friend had become obese. A sister or brother of a person who became obese had a 40% increased chance of becoming obese. The risk for a wife or husband was a little less than that. Nicholas Christakis of Harvard Medical School was a lead researcher in the study. He says there is a direct causal relationship between a person getting fat and being followed in weight gain by a friend. The study found that the sex of the friends was also an influence. In same-sex friendship, a person had a 71% increased risk of becoming obese. Men had a 44% increased risk of becoming obese after weight gain in a brother. In sisters, it was 67%. The researchers also considered the effect of where people lived in relation to each other. James Fowler of the University of California was the other lead expert. He says a friend who lives a few hundred kilometers away has as much influence as one in the same neighborhood. He says the study demonstrates the need to consider that a major part of people's health is tied to their social connections. Both researchers say their research shows that obesity is not just a private medical issue, but also a... The author makes his point clear in the text that _ . A) a major part of people's health is based on their genes B) friends living closer have greater influence on one's health C) social relationship is closely connected with people's health D) people's physical condition is subject (,......) to social connections
A: C
*Question*
Kayaking is an activity enjoyed by many people of all ages. It requires little or no experience and nearly anyone of any skill level can participate. It's most popular as a summertime sport, but it is also a great activity during the winter. Kayaking also seems ly friendly to the environment; more so than speed boating or water skiing. Because a kayak doesn't create large or frequent waves, require fuel, or scatter hazards into the air, it is indeed a fairly safe activity for humans and wildlife alike. Kayaking on freshwater lakes and streams creates little turbulence and therefore does not disturb fish or other aquatic life. Actually, the gentle paddling and movement of the kayak helps to bring seaweed to the surface, making for convenient snacking to the fish. However, there is a drawback to the all-you-can-buffet for your fishy friends. In addition to bringing food to the surface, kayaking also stirs up litter that's been hiding beneath the waters. Some aquatic animals will mistake it for food. This could cause the animals to choke on the indigestible litter, leading to death. As hazardous as this sounds, it isn't very likely for such an event to take place. Most litter in lakes and streams is found along the shoreline and settles in the sand and dirt, and isn't likely to drift away to the main body of water. ^ . And because kayaks do not have a motor, fish have no risk of getting caught underneath the boat. One potential hazard that results from kayaking is human waste. This depends solely on where you plan to kayak, and if there are resources available (such as campsites) along the shoreline. When there are no facilities in sight, you're paddling in the middle of a lake, and nature calls, then often you are given no choice but to expel your waste in the middle of the water. While human waste is considered biodegradable, it can be harmful when swallowed by fish. The only preventative measure is to avoid using the water as a restroom. Some public lakes and streams have taken steps to preserve the... Which is the best title of the passage? A) The environmental impacts of kayaking--is it dangerous? B) The most popular water sports--kayaking C) Advantages and disadvantages of kayaking D) How to keep kayaking a safe and enjoyable activity?
**Answer**
A