Many people may not believe it, but this is what is happening: polar bears are dying out! They are dying because they are losing a great deal of habitat due to human incursion and global warming. They are dying because of starvation as well. With the sea ice they depend on for survival shrinking, it is becoming increasingly difficult for them to find food. An ecosystem is highly dependent on all of its parts, and removing even a single species can result in serious consequences. Polar bears are at the top of the predators where they live. They play an important part in the ecosystem. They feed on seals, fish and deer. Several other animals depend on the kill of polar bears. The failure to save polar bears might result in loss of these predators. In addition, all large predators perform a very important function in their habitat: helping to control the populations of other species. When an animal group loses its natural predators, its population will rise rapidly, having a direct result in population decrease of other groups. A huge boom in population of Arctic seals would have a direct effect on the prey of seals, and could reduce numbers of certain types of fish. This could also have a direct effect on humans, who might have to compete with Arctic seals for food supplies from fish. Lack of polar bears could eventually affect human food supply. Human beings shall save polar bears to ensure the food supply. There is no doubt that we should save polar bears. However, there is still another question: can they be saved? This is a matter that scientists debate because of rapid degradation of the polar bear' environment in recent years due to warming temperatures. It is estimated that if the bears cannot adapt to changing climates, they might die out before the end of the 21stcentury, with about 50% of the animals disappearing by 2050. So time is running out! There are some things that may help slow down global warming and help delay extinction of polar bears. These include finding new energy sources... Which is NOT the threat to the survival of polar bears according to the passage? A) Human's killing. B) Global warming. C) Habitat loss. D) Lack of food.
A
(Question)
Once again, rumors are spreading. Judgment Day, this time, is set to happen on December 21st, 2012. The date originated from the Mayan calendar, but actually gained popularity through the hit movie, "2012". How will the world end? And how do we know the exact date? There are many theories: A meteoroid from outer space; a solar storm; a shift in the earth's poles; bla bla bla. They all supposedly pointed to the date of December 21st, 2012. Unfortunately, none of it is true. Zhu Jin, director of Beijing Planetarium, said, "For earth itself, the end will be billions of years away from now.And for us humans, there is a very small chance that we may be affected by some astronomical factors.However, we don't have the ability to foresee such events so far.So when someone tells you the world is going to end on an exact date, it must be fake." But the truth hasn't stopped people from believing. In the sci-fi movie "2012", the director imagined the end of the world based on the Mayan calendar. The film earned nearly 770 million US dollars worldwide. Ning Hong, Hebei Province, said. "The movie 2012 did get one thing right. There are arks being made in China, But they're not being built secretly inside the mountains.They are constructed here in the courtyard of a factory." In April, Liu Qiyuan quit his furniture business and devoted himself to developing these huge round balls. He doesn't believe the end is near, but he wants to be prepared just in case. Liu Qiyuan, the "Ark" builder, said, "The concept originated twenty years ago. The Tangshan earthquake had flattened our house, so I wanted to build a shelter that wouldn't fall. Then in 2004, I saw the tsunami in Indonesia that killed so many people.Then I realized it should be something that could withstand the earthquake and float on water." Liu is hoping to use his invention as a life boat on the sea.He's planning to test his product on the water next year. It turns out that rumor, though false, is good for business. Doomsday discounts and products are hot on... Liu Qiyuan quit his job and built his "ark" because _ . A) he wanted to make preparations for destructive natural disasters B) he was tired of making money from his furniture business C) he was almost killed in Indonesia in 2004 D) he believed that the world was going to end on Dec. 21, 2012
(Answer)
A
In many sports, physical contact is part of the game. But when athletes hit their heads, the hit can cause concussions . Concussions have long been a concern for professional athletes, but they've become more common among young players too. Between 2001 and 2009, the number of kids under 19 visiting doctors for concussions each year increased by 62 percent. Engineers are developing new helmets , and new rules are limiting physical contact in some sports. But are these efforts enough to protect kids' brains? Concussions can happen during many types of activities. But sports like football and soccer are especially risky. When you run or jump, your body is moving at an increased speed. A sudden hit causes you to move faster in a different direction. "It's like when you're in a bus and it makes a sudden stop," says Dr. Kevin Crutchfield, an expert at a sports concussion center in Baltimore, Maryland. "You hit the inside of the bus." This hit damages the brain. It affects the way the brain functions. So some sports require athletes to wear helmets. Helmets help reduce the force of a hit. The hard outer shell spreads the force of larger area. Inside a helmet, a plastic or air-filled lining also helps soften the blow. Steve Rowson is an engineer at Virginia Tech. In his lab, he tests how helmets hold up against different types of hits. No helmet can prevent concussions completely, says Rowson. But he's found that when wearing a newer football helmet, the player's head doesn't gain speed as much after a hit. That lowers the risk of concussions. Many youth sports teams have set limits on physical contact to reduce the risk of concussions. In soccer, most concussions happen as a result of headers--shots or passes made with the head. That's why many people think kids shouldn't head the ball until high school. These efforts should help, says Crutchfield. But the best way to prevent long-term brain injuries, he says, is to stop playing immediately if you suffer concussion. "Protect yourself today so you can play again tomorrow." Dr. Crutchfield suggests that after receiving a concussion, young players should _ . A) never head the ball B) avoid dangerous sports C) play other kinds of sports D) stop playing the sport for a while
D