阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。

    With his unique black mane (鬃毛)and impressive stature(身材), 13-year-old Cecil was a popular tourist attraction at the 3.6 million-square-acre Hwange National Park(万基国家公园) in Zimbabwe (津巴布韦).

    Cecil was head of a pride of lions that includes 12 cubs(幼崽), but the well-known lion was shot and killed in early July by American dentist Walter J. Palmer.  

Cecil's death has already sparked an international outcry (强烈抗议) with many calling for an end to hunting endangered animals and for Palmer to be extradited(引渡) to Zimbabwe to stand trial.

Professor David Macdonald, the head of the Oxford University research program that monitored the daily movements of Cecil and dozens of other lions, is deeply saddened by Cecil's death. Macdonald hopes the death can inspire the public to take an interest in lion conservation.

    Macdonald says many of the lions tracked by the program have been shot  and killed. “The background to this story is that there is a crisis for lions throughout much of Africa.” He says.

    African lion populations have fallen almost 60 percent over the past thirty decades, and as few as 32,000 of them remain in the wild, according to the International Fund for Animal Welfare(国际爱护动物基金会).

“And as troubling as it is, the rarer these hunted animals become, the more hunter s are willing to pay to kill them,” said Jeff Flockedn, the fund's North American regional director.

    In addition to excessive hunting, lions throughout Africa also continue to face threats that include conflicts with local farmers, loss of habitat and risk of traffic and railway collisions(碰撞).

Distance runners often worry about “hitting the wall” during training or races—that terrible moment when negative thoughts become so overpowering that they make it difficult to continue.

Hitting the wall typically happens around 20 miles in a marathon, when the body's supplies become exhausted. At this point, many runners feel exhausted and discouraged, slow their pace, have trouble focusing and want to quit or walk.

“Generalized tiredness, unintentionally slowing their pace, the desire to walk, and shifting focus to just surviving the marathon appear to be particularly common characteristics of it,” said Dr. Alistair McCormick, an exercise psychologist in England who co-authored a new study. “A marathon becomes a real mental battle when runners ‘hit the wall.'”

    Psychological blocks are an extremely common experience for recreational endurance (耐力) athletes, according to the study. To learn how they affect people, sports psychologists asked 30 recreational runners and cyclers about the psychological demands of training, preparing for and participating in competitions.

     “Recreational runners and cyclists found it stressful trying to find the time to train, McCormick said. “What was also interesting was the number of potential banana skins they met with before and during competition-disasters that could cause the athletes to lose their focus and their motivation to keep persevering.”

    These roadblocks included difficult environmental conditions and equipment failure, problems with nutrition or making a mistake, the study reported. The athletes in the study said they fell these obstacles (障碍) affected their motivation and concentration, negatively affecting their overall performance.

According to the study, 43 percent of marathoners are likely to hit the wall during a race. Finding ways to move past those kinds of experiences, then, could have major benefits for an athlete's performance and well-being.

    Science fiction writers create imaginary worlds. The way things work in your imaginary worlds will be based on actual science. So it's important for you to be familiar with the scientific principles and inventions that are related to your creation. For example, if you're writing about human living on a planet with zero gravity, then you need to know the effects of zero gravity on the human body.

    Then you have to figure out the exact rules of your imaginary worlds. And you have to follow them. If humans are able to breathe underwater in Chapter 1, your character can't drown in a swimming pool in Chapter 3. The issue here is maintaining your readers' trust. That means the readers are willing to pretend along with you. If you start out with an ordinary detective novel and then throw in someone breathing underwater in the 6th chapter, you will pull the readers out of their imagination. The same thing happens if you change the rules halfway.

    Part of your preparation work for the novel is to map out its worlds in great detail. You should decide the following issues: the history of the world, the geography, what possibilities it offers, how everything works in this new reality, and how all of these factors affect the way your characters think, feel, and react to things. You don't have to tell your readers all the rules in the first chapter. But you have to let readers know enough to understand what's going on. This also allows you to work out logical problems and contradictions before you start writing.

    When you are writing, remember to make it feel real. You are inviting readers to visit a new world. They will want to be able to see, hear, feel, smell, and even taste what it's like. Whether your novel is about a world without disease or an undiscovered planet, help your readers feel like they're actually there.

    When I was about 4 years old, I decided to go to Disney World. For most young kids, it's a normal request, but I had cerebral palsy(脑瘫).Walking into anywhere, let alone a crowded place like Disney World was, to put it lightly, a tall order. Luckily, I had people in my corner to help me. Over the next three years, I worked with physical doctors, acquired a walker, and practiced walking, standing, and balance—all skills that I would need to turn my goal into a reality.

    I remember the feeling when my legs would protest doing any more work. Despite this, everyone else told me I could do it, so I kept it up. It was all because of people like my parents, brothers, teachers, and doctors that I was able to grow so much, both physically and mentally. Constantly pushing me to “walk on,” yet encouraging me whenever I needed it.

    On June 9, 2008, as I stood in the tunnel leading into Main Street, My dad asked me if I wanted any help. I instantly replied, “No!” and situated myself facing the end of the tunnel, feet planted firmly, heart most likely beating out of my chest. Then I went, walking ever so slowly at first, then gradually speeding up. Step, step, step, step, bump. Holding fast onto the handlebars, I gathered up all my strength, picked up my walker and straightened out, picking up my pace once again. It wasn't too long before the cheering increased because I had made it to the end, where my mom was waiting with tears in her eyes and arms open wide ready to hug her son and tell him how proud she was.

    Looking back on that experience, I realize something pretty thoughtful. Every once in a while, life will throw a few bumps in the road. Though it may set you back for a bit, don't let it stop you. Pick yourself back up and finish. It's worth it. Besides, there just might be someone there cheering you on along the way.

    It takes a special person to travel with kids—a parent. Children have their own needs. Their idea of a vacation is more “adventurous” than a parent's. They need constant inspiration and they can get as tired as they are tiring.

    Make sure you have plenty of room while traveling

    If you are driving, get a mini-van. Sure, you might be more of a “car” type, and you might have resisted buying a mini—van so far. But pick up a rental van for the vacation just to give the kids a little more room for fighting.

    Accommodations along the way can be tricky. Usually it involves a crowded motel for just long enough to sleep, then back in the crowded car. This is not anybody's idea of a home away from home. An accommodation alternative is to camp, but not everyone enjoys a good early morning wake-up wrestle with a bear as much as I do, so a motel might be required.

    Make sure you have plenty of room when you “get there”

    Assuming you are actually heading for a destination, make sure to have lots of room when you get there. This part is easy. But it requires thinking outside the box. Forget hotels, motels, and inns. Look for private rental homes.

    Probably the biggest destination for families is Walt Disney World in Florida. Good news—Orlando, Kissimmee and the surrounding area is full of private vacation homes for rent. In Florida they call them vacation villas, and they offer all the space of home.

    Be prepared for “children being children” events

    Sometimes, stress hits you from behind when the unexpected happens. Like a cut or a scrape…or a child getting sick. Sharon Baillie told me that is why she tells all her villa rental guests where the first-aid case can be found, and exactly where to go for medical attention. This is particularly helpful for her many guests from abroad, who are unfamiliar with the US healthcare system.

    Booking tickets to theme parks and making reservations for just about everything in advance makes the trip less stressful. Try having your children baby-sat. Hire a local baby-sitter once or twice. Vacation Home owners can set this up for you, and some hotels might be willing to, too.

    A smile will tell people around you that you are a kind and friendly person. However, many people don't smile because they think they have ugly teeth. For example, one of my classmates, Mike, doesn't have very nice teeth, so that is why he seldom opens his mouth. He even says that he has lost confidence because of his teeth. So it is very important for us to look after our teeth. In fact, a lot of people have this problem. Some people inherit tooth problems from their parents, while others' teeth are damaged because of bad habits, like heavy smoking, eating too much sugar or not brushing teeth often. If your teeth are in bad shape, you should see a dentist and ask for help. They can help improve your teeth and tell you how to take care of them.

    Smiling can help you feel more confident and make people think of you as a more friendly person. If you want to keep healthy, you should not only smile but also laugh. An Indian doctor called Kataria said that young children should laugh about 30 times a day, while adults should laugh between 7 and 15 times a day. So please take this chance to smile and laugh now.