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).

    Do you ever wonder why trees begin to bud (发芽) earlier in some cities? Scientists finally found the answer but it's not very pleasant. New science suggests a relationship between light pollution and the timing when trees produce buds, which signals the arrival of the spring season.

    Light pollution is defined by the Lighting Research Center as the unwanted consequence of outdoor lighting such as street lights. Excessive (过多的) man-made light at night results in disturbed natural cycles, and also prevents the observation of stars and planets at night. But its effect on the environment goes beyond that.

    By studying some trees, researchers found out that trees that are more exposed to artificial lighting at night bud up to 7.5 days earlier than those at the natural nighttime setting. And they found out that light had a more significant effect than temperature when the buds came out. The early budding may cause problems for insects, which feed on leaves, and the birds which then feed on them in turn. Professor Richard Ffrench-Constant, who helped lead the research, explained that more than the budding of trees, the study implies the danger to the balance of the ecosystem. “At the moment, caterpillars (毛毛虫) are timed to hatch to make the most of the opportunities to feed on freshly budded leaves, and birds hatch in time to feed on the young caterpillar,” he said.

    Migratory (迁徙的) birds are also negatively affected by light pollution. The glare might confuse them and make them lose their flying sense. The phenomenon might explain why some birds accidentally knock into buildings.

    Such results stress the need to pursue studies that aim to measure the effect of light pollution. If the issue were left to continue, it is estimated that by 2100, spring would begin almost a full month earlier than it does today.

With fuel costs rising and airlines finding more fees to impose （强加，征税）on travelers every day, airfare isn't getting any cheaper. Since you can't drive to all your dream destinations, flying is the only way to go sometimes and, undeniably, the fastest. Luckily, there are plenty of ways to find the most affordable fares and also avoid paying as many extra charges as possible when you plan ahead.

    Get the best fare. Airlines put out their fare sales on Tuesday morning, making this day the best day to book a flight for less.

Fly during the least popular times. Tuesday, Wednesday and Saturday are the slowest days to fly, which means cheaper deals than the rest of the week. You can also find reduced rates on early morning flights, since many people don't like to get up before the sun to get to the airport. Earlier boarding times can also considerably cut down your chances of getting bumped on an overbooked flight or delayed because of other delayed flights or mechanical issues.

    Choose your seat later. Some airlines charge you to pick your seat when you book online, adding even more to the bottom line of your ticket cost. If you show up early on your travel day, you can still get suitable seats. Some of the best seats get held back until flight day, unless others are willing to pay extra for them ahead of time, so you still have the chance at one of those.

Fly on holidays. You already know that summer is the most expensive time to fly, and even though most other times are more affordable, the days surrounding holidays can be crazy. Save big if you're willing to travel on major holidays, such as Thanksgiving and Christmas.

Don't wait until the last-minute to book. Many travelers don't know that there's a sweet spot for booking and getting the best price on your tickets. Book too early or too late and you could end up paying more than you need to. The best time to book is between three months and six weeks from when you want to travel.

    Billie Holiday was an American jazz singer and songwriter. Nicknamed Lady Day by her loyal friend and musical partner, Lester Young, Holiday had a great influence on jazz and pop singing. Her voiced style, strongly inspired by jazz instrumentalists, pioneered a new way of controlling tempo (节奏). Above all, she was admired for her deeply personal and direct approach to singing.

    She co-wrote a few songs, and several of them have become jazz standards, notably God Bless the Child, Don't Explain, and Lady Sings the Blues. She also became famous for singing jazz standards written by others, including Easy Living and Strange Fruit.

    Her early career is hard to track down with accuracy. But she later gained work singing in local jazz clubs before being spotted by a talent scout (星探), John Hammond in 1933.

    Her voice and recordings were loved for the depth of emotion and intensity she could bring to classic standards. Her range of voice was not the greatest, but her extraordinary low rough voice was soon to become very famous and influential.

    She was an important icon (偶像) of the jazz era and influential in the development of jazz singing. In the late 1930s, she began singing a civil rights song called Strange Fruit, a song which told the tale of a lynching (用私刑处死) of a black man in the Deep South. It was very controversial for that period and it was not played on radios. It was recorded for Commodore Records and she performed it many times over the next 20 years.

    Billie Holiday had a difficult upbringing which influenced her attitude toward life. She experienced many violent relationships. She also became increasingly dependent on various drugs which contributed to her early death in 1959, aged just 44.

    There is one type of illness in the world that has a severe effect on more people than anything else and is very deadly. If untreated, this illness could affect everything you do. What is this illness? Depression. Serious depression requires professional treatment. Self-induced depression is something each of us can change.

    Everyone's circumstances are different, but the causes of self-induced depression are common: low self-esteem, hurtful thinking and a bad attitude.

    So how can we change the way we think, feel, and have a cheerful attitude?

    First we must look at ourselves, truly and honestly examining our motives for what we wish to accomplish. If you are dissatisfied because you feel you haven't or can't do anything, then one step is needed—to set goals.

    Always start your goals relatively small and easy to attain. Think of them as sand; one grain may be insignificant(微不足道的) but as a group they form the beach. Once you have set and attained small goals for yourself, move on to slightly larger, more challenging goals.It takes not just setting goals but positive thinking. How can we obtain this?

    There are a number of factors that can make us think negatively and one of those is diet.In my opinion, a person who eats a lot of take-out and fast food is feeding their body junk. Start by eating better foods which give the body much NEEDED minerals. If your physical body is happy, it's much easier for your mental body or “thinking ability” to be happy.

    Next, exercise. Half an hour a day is recommended for positive well-being. Then think about good memories you had, or generally think of things that make you smile. Remember, everything you wear costs money but to wear a smile is free. A smile can be the difference between an average day and a great day.

    If you follow these steps, positive change is on the way.

    China now has 52 sites included on the UNESCO World Heritage List, which was established to safeguard unique and irreplaceable cultural and natural sites around the world. Let's have a look at some of them, which may give you some clues on your next travel plan.

    Mausoleum of the First Qin Emperor

    The Mausoleum of the First Qin Emperor is located in Lintong county, near Xi'an city, capital of Shaanxi province. A total of 8,000 life-size terracotta warriors, chariots and horses, and hundreds of bronze weapons have been unearthed from it. Many state leaders and experts worldwide believe that the discovery of the mausoleum is a major archeological find and can be called the eighth wonder of the world, paralleling Egypt's pyramids.

    Kulangsu, a Historic International Settlement

    Gulangyu Island, known in the local dialect as Kulangsu, is located on the entry of the Jiulong River, facing the city of Xiamen. The island was occupied by at least a dozen countries, including Great Britain, France and Japan. As a result, Western culture grew rapidly there in the 19th century, especially music. With such a harmonious blend of Western music and Eastern culture, Gulangyu is naturally referred to as the "island of music". It is famous for its outstanding musicians and musical instruments.

    Qinghai Hoh Xil

    Hoh Xil, which means "beautiful girl" in Mongolian, is located in the north-eastern end of the Qinghai-Tibetan Plateau. Hoh Xil National Nature Reserve is China's largest and the world's third largest uninhabited area. Because of the high altitude and fierce weather, it is impossible for people to live there, and therefore, it is a paradise for wildlife and home to more than 230 species of wild animals including endangered species such as the Tibetan antelope, which is recognized as the National Class I Protected animal.

    Huangshan Mountain

    Huangshan, known as "the loveliest mountain of China", lies in the south of Anhui province in eastern China. The scenic area covers 154 sq km, and is famous for its peaks, rocks, pines, clouds and springs. It also has a rich cultural heritage. Xu Xiake, a famous traveler of the Ming Dynasty (1368-1644), visited Huangshan twice, and described it in a poem, calling it the best of all mountains in China. Today it holds the same fascination for visitors, poets, painters and photographers.