. As the world's largest terrestrial carnivore ,the polar bear is the king of the great white north. Adult males can measure more than 9 feet in length and weigh between 770 and 1,430 pounds. The bear's body and neck are elongated, and the head is narrow and long with small, rounded ears. Polar bear populations can be found in northern Canada, Greenland, Norway and Russia, and there have been reports that polar bear tracks have been found as far north as the North Pole. The 5,000,000-square-mile range of the polar bear circles the Arctic and contains stretches of open water where seals are easily caught. Polar bears live on the annual Arctic sea ice that provides a platform from which they can hunt. They hunt seals on the sea ice by breaking into seal dens in the sea ice. The dens aren't visible from above,but seeing is less important than smelling to a polar bear -- with their keen sense of smell,polar bears can sense the breathing holes of seals in their dens beneath the snow and ice. As the southern edge of the Arctic ice cap melts in summer, polar bears are stranded on land and spend their summers fasting ,living off body fat stored from hunting in spring and winter. It might come as a surprise that this species faces an uncertain future. Climate change is causing the disappearance of sea ice from which polar bears hunt seals. Sea ice in the Arctic is melting earlier and forming later each year. With about 22,000 polar bears living in the wild,the species is not endangered at the moment, but its future is far from certain. People have reached an agreement that controls the hunting of polar bears and directs each nation to protect their habitats, but it does not protect the bears against the biggest man-made threat to their survival : global warming. If current warming trends continue, scientists believe that polar bears may disappear within 100 years. It can be inferred from the passage that _ . A) the polar bear is an endangered species at present B) we should protect seals in order to keep the food chain in the Arctic C) the polar bear can be found near the North Pole and the South Pole D) people will do something to protect polar bears
D

Prolonging human life has increased the size of the human population. Many people alive today would have died of childhood diseases if they had been born 100 years ago. Because more people live longer, there are more people around at any given time. In fact, it is a decrease in death rates, not an increase in birthrates, that has led to the population explosion. Prolonging human life has also increased the dependency load. In all societies, people who are disabled or too young or too old to work are dependent on the rest of society to provide for them. In hunting and gathering cultures, old people who could not keep up might be left behind to die. In times of , infants might be allowed to die because they could not survive if their parents starved, where as if the parents survived they could have another child. In most contemporary societies, people feel a moral to keep people alive whether they can work or not. We have a great many people today who live past the age at which they want to work or are able to work; we also have rules which require people to retire at a certain age. Unless these people were able to save money for their retirement, somebody else must support them. In the United States many retired people live on social security checks which are so little that they must live in near poverty. Older people have more illnesses than young or middle-aged people; unless they have wealth or private or government insurance, they must often "go on welfare" if they have a serious illness. When older people become or too weak and ill to care for themselves, they create grave problems for their families. In the past and in some traditional cultures, they would be cared for at home until they died. Today, with most members of a household working or in school, there is often no one at home who can care for a sick or weak person. To meet , a great many nursing homes and hospitals have been built. These are often profit making organizations, although some are sponsored by religious and other nonprofit... It can be inferred from the passage that in hunting and gathering cultures _ . A) it was a moral responsibility for the families to keep alive the aged people who could not work B) the survival of infants was less important than that of their parents in times of starvation C) old people were given the task of D) death was celebrated as a time of rejoicing for an individual
B

"It's really cool to have a dad who flies fighter jets,"thought 11-year-old Casey as she was watching him fly overhead. Living on an Air Force base was not as bad as some people might think. Casey rather enjoyed being around friends who had something in common with each other. They had their own school, bowling area, and movie theatre. She especially loved it when her dad would come home each day and greet her with a new joke and tickles. Today was different, though. When her dad walked into the room, he looked sad for some reason. He just kissed her on the forehead and told her mum that he needed to talk to her. Casey knew something was wrong. When her mum and dad came out of the other room, mum was crying. Dad sat down and began to explain that he has been called to go to Iraq to help with the war effort. Casey was so surprised that she couldn't speak for a moment. She began to feel tears in her eyes. How could she live without her dad for a whole year? Soon, the day came. Her dad was leaving. As Casey and her mom watched him climb up the steps to his cockpit, the tears began to flow and it felt like _ would never end. It was hard for Casey to believe that she wouldn't be seeing her dad for so long. They depended on him for so many things. Who would fix the broken window? Who would greet her with jokes and tickles at the end of the day? And then the thought hit her, " What if he doesn't make it home?" Casey began to sob more than ever. What can we know from the story? A) Casey's dad volunteered to help with the war. B) Casey's parents didn't let her know the truth. C) Casey's dad amused her in the morning usually. D) Children living on the base could see movies in their theater.
D