Starting in l972,the National Park Service established a policy for forest fires calle Natural Burn.It was acknowledged that some forest fires,such as those caused by lightning were necessary for forests to maintain balanced ecosystems,so the fire should be allowed to burn.However, a big fire in Yellowstone National Park in l988 caused this policy to be abandoned since the fire was initially allowed to burn yet soon out of control.As a result,the fire of l988 destroyed much of Yellowstone,which is America's oldest and most beloved national park.Massive areas of plants were destroyed,and large empty spaces and acres of burned and blackened trees greeted visitors.The rivers and streams were choked with ash,and the ecosystem of the park was changed beyond repair. In addition,great numbers of animals were killed by the fires that bumed out of control. The fires were driven by high winds,moving as many as ten miles a day.Many small animals died in the flames.The fires' rapid advances gave the wildlife little chance to escape. Even today,few of these small forest animals have returned to live in the park. In the years immediately following the fires,the numbers of visitors declined rapidly.No one was interested in seeing a blackened and treeless park on vacation.Yellowstone had previously been famous for its amazing views and unique geological formations such as the geyser Old Faithful. But now its reputation as America's wonder is damaged permanently. Natural Burn was adopted because some forest fires were A) hard to put out B) started by lightning C) good for the balance of nature D) approved by National Park Service
C

Film director James Cameron first became interested in sea exploration when he was a little boy.His love for the ocean grew after he made the 1989 undersea adventure film The Abyss and the 1997 blockbuster Titanic,one of the most successful movies of all time.Following that big success,James Cameron decided to put his film career on hold to become an explorer. In 2012,James Cameron made a journey to the deepest spot in the Mariana Trench,known as Challenger Deep.And now the great journey has been made into a documentary film,named James Cameron's Deep-sea Challenger 3D. In James Cameron's fantasy films,such as Avatar and The Abyss,the unexplored areas are decorated in colors and full of danger.But on his dive into Challenger Deep,the reality proved far different: white, deserted and dull. "I felt like I had gone to another planet,"Cameron said after returning from the cold and dark place in the Western Pacific Ocean,nearly 7 miles below the surface."I really have a sense of being separated and realize how tiny I am down in this big, black and unexplored place." Cameron captured the moon-like landscape of the deep sea and documented the sea creatures he observed in the ocean. James Cameron's Deep--sea Challenger 3D tells the story of Cameron' s journey.It is a film about determination,danger and the ocean'S greatest depths.The movie shows a unique insight into Cameron's world when he makes his dream reality and makes history by becoming the first person to travel alone to the deepest point on the planet. It's an exciting film and inspiring reminder that our beautiful planet still has a lot to explore. What can we know about James Cameron's Deep-sea Challenger 3D? A) It is a film about the exploration of ocean creatures. B) It is a story about Cameron's film-making dream. C) It aims to attract more people to explore the deep sea. D) It tells us about James' journey into Challenger Deep.
D

One kind of female butterfly mates only once in its life -- and then closes its wings to avoid _ " when pursued by persistent and unwanted males, a Japanese researcher said. Observations of the Small Copper Butterfly, a colourful orange and black butterfly, showed that some females closed their wings when males flew by, but only when they were males of their own species, said Jun-Ya Ide, an associate professor at Kurume Institute of Technology in Fukuoka, western Japan. "When we looked into why, the males were courting the females. They do this very stubbornly, so the females sometimes try to get away -- or prefer to stay unobserved," he added. Ide and his colleagues brought a model of a male butterfly near the females to test their reactions and found that young females that had yet to mate kept their wings open, but those that had already mated closed them. Not only can the persistent attentions of unwanted suitors harm the delicate females, fleeing from them -- with the male often in pursuit -- uses up strength and can even shorten their lives, he added. "Closing their wings makes them less visible, helping them avoid communication with their own species. We figured they were trying to avoid harassment by males," Ide said. Why some some females closed their wings when males flew by? A) because they close their wings to avoid "harassment" when pursued by persistent and unwanted males. B) because the female butterfly mates only once in its life. C) because they don't like the male butterfly at all. D) because they are afraid of the male butterfly.
A

It is love that makes the world go round. And it is also love that has such power to overcome all difficulties. So we say: "Love will find a way." As smile is a facial expression showing pleasure, affection, and friendliness, it is the commonest way to show our good will perfectly without saying anything. A Chinese saying runs: "never hit a person who is smiling at you." It is a time-proven fact that the smile is a language all its own-- a universal language--understood by the people of every nation in the world. We may not speak the same tongue as our foreign neighbors, but we smile in the same tongue. We need no interpreter for thus expressing love, happiness, or good will. One day while shopping in a small town in southern California, it was my misfortune to be approached by a clerk whose personality contradicted mine. He seemed most unfriendly and not at all concerned about my intended purchase. I bought nothing, and marched angrily out of the store. My anger toward that grew with each step. Outside, standing at the corner, was a dark-complexion young man in his early twenties. His expressive brown eyes met and held mine, and in the next instant a beautiful, dazzling smile covered his face. I gave in immediately. The magnetic power of that shining smile drove away all bitterness within me, and I found the muscles in my own face happily responding. "Beautiful day, isn't it?" I remarked, in passing. Then, suddenly something inside me sent me turning back. "I really owe you a debt of gratitude," I said softly. His smile deepened, but he made no attempt to answer. A Mexican woman and two men were standing nearby. The woman stepped forward and eyed me inquiringly. "Carlos, he no speak English," she volunteered. "You want I should tell him something?" In that moment I felt transformed. Carlos' smile had made a big person of me. My friendliness and good will toward all mankind stood ten feet tall. "Yes," my reply was enthusiastic and sincere, "tell him I said 'Thank you!'" "Thank you?" The woman seemed slightly... The author got angry while shopping one day because _ . A) of the clerk's unfriendliness and lack of concern B) of her misfortune C) she failed to purchase what she intended D) a dark-complexion young man laughed at her
A