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。

    A recent announcement by scientists that they have successfully cloned the first human embryo(胚胎) has caused much debate and has shocked many people around the world. On the one hand, some scientists point out that if you clone an embryo, you can produce valuable tissues(组织) and organs that could be used to save human lives. On the other hand, many people, including some scientists, disagree and fear that if mankind interferes with (干涉) nature in this way, they may be on their way to producing a real-life Frankenstein's monster.

Cloning is producing an exact copy of a plant or an animal using its cells. The first mammal to be cloned successfully from an adult cell was Dolly—the sheep. She was born in 1996 and died in early 2003, at a much younger age than normal. When she was born, many people were angry because they thought cloning would create more diseases in the animal world. However, in general the scientists were praised for their wonderful scientific breakthrough.

    The Scottish scientist who created Dolly, Ian Wilmut, is shocked that some scientists are now considering cloning human beings. Although he researches cloning, he has never thought of creating copies of humans. Instead, he thinks the scientists should concentrate on creating new tissues and organs that could eventually be used to cure diseases like cancer. However, some people consider that cloning human embryos with the intention of destroying them shows no respect for human lives.

    While cloning human embryos is illegal in many countries, some scientists are already pushing ahead with the research so as to deliver a cloned human baby. Severino Antinori, an Italian doctor, is one of the leaders in this field of research. He has declared that he wants to be the first to clone a human being.

In China, scientists have focused their efforts on cloning animals, as well as stem cells to be used in medical research. China has succeeded in producing clones of cows and goats, and continues to research ways in which cloning can benefit mankind.

    You've probably visited the Tian'anmen Gatetower—the landmark building of Beijing, but you may not have heard of Kuai Xiang. Along with him, the following remarkable architects all took the center stage at their times.

    Kuai Xiang(1399—1481)

    Tian'anmen Gatetower is universally considered the brainchild of Kuai Xiang. By following in the footsteps of ancient homebuilders, he successfully presented the Emperor Judy with a grand wooden structure which has stood the test of time for almost 600 years. Visitors are also hooked on its delicate paintings.

    Ieob Ming Pei (1917-present)

    His motto is: Traditions should be sealed in glass boxes at museums. He is always struggling with innovation. Although under grilling from French conservative critics, he still planted a glass pyramid into the courtyard of the Louvre. His other works include John F. Kennedy Library, Beijing Fragrant Hill Hotel and Suzhou Museum.

    Zaha Hadid(1950-2016)

    In 2004, she became the first woman to win the Pritzker Architecture Prize, the Nobel Prize for architecture. She used tricks to maximize available space. Her fluid-style works pioneer the concept of micro-living. The curves(曲线) of Guangzhou Opera House perfectly match the rise and fall of its surrounding buildings, forming a unique view.

    Meng Fanchao (1959-present)

    Many people dismissed the building of a mega bridge as a pipe dream, but Meng Fanchao turned this into reality by building Hong Kong-Zhuhai-Macao Bridge. This longest cross-sea bridge, when viewed afar, looks like a dynamic dragon braving the rolling waves of Lingding Sea.

    With all the wars, fighting and sadness in the world today, it's not only necessary, but also essential to have a good sense of humor just to help us get through each and every day of our lives. Putting a smile on someone's face when you know they are feeling down in the dump, makes me feel good and warms my heart.

    How would you feel if you could not joke around with your wife, husband, child, co-worker, neighbor, close friends, or even just someone that you are standing in line with at your corner store? I am always saying things that make others smile or laugh, even if I don't know the person I'm joking around with. My Grandma always found humor in everything she did, even if it was the hardest job anyone could imagine. This not only relieves stress in any situation, but also is common courtesy(礼貌)to speak to others that are around you.

    I know of a few people that don't have a funny bone in their bodies, as they say. Everyone around them could be rolling on the floor after hearing a great joke and they would sit there without the s lightest smile on their face. They don't get the joke that makes others laugh. I am busting a gut while they just sit there, looking at me as if I were from outer space. How can people not get a really funny joke?

    Laughing is essential to keep your stress levels under control. Without humor we would find ourselves with a lot of psychological problems, or on a lot of medications to keep us from going crazy. There is too much sadness in this present world. It drives people crazy. We all need to find a way to ignore the sadness and bring a little light into our lives. So, I believe our best medicine is to get together and tell some jokes and have some fun laughing together.

    Reader: For six years, I've run an office that has two employees: me and my boss. He used to be so appreciative that I didn't mind doing a little extra, but about two months ago, he started being rude and demanding. Now he even yells when I don't have time to bring his favorite wine to his home after work.

    This change started when we met a wealthy new customer, who is a huge jerk (古怪的人) — my boss's new behavior is just like his.

    My boss is a good man; he and his family have treated me like a little sister. Is there a good way to discuss this with him?

    Karla: Sounds like your new customer has set a bad example to your boss. You need to remind your boss that you're in his corner— but you're not his slave. My suggestions are as follows.

Start with a simple question in a calm moment: "Is everything okay?"

State the truth: "Until recently, I've felt like a valued teammate. But our relationship has become tense. Your expectations of me seem to have changed. Although I used to do occasional personal businesses for you as a favor, now it seems expected."

Draw your lines: "If you think my job description needs to change or my performance is not good enough, let's discuss that. Otherwise, I need you to stop yelling at me and to respect my personal time."

Ideally, you'll get an apology and a promise to do better. After that, it's a matter of reinforcement (加强) . If he starts yelling, look at him with a calm expression. After he cools down, restate his request and add, "Is that correct?" For the unreasonable request, such as fetching his favorite wine after work: "I'm afraid I can't take care of that for you." If he keeps acting like a jerk, there are bosses out there who will better respect your time and talent.

    Karla L. Miller is ready to hear your work dramas. Send your questions to wpmagazine@washpost.com.

    Being able to land safely is a critically important skill for all flying animals. Comparatively speaking, ground living animals face no particular challenge when they need to stop running or crawling, while flying animals move at much higher speed, and they must be careful about how they land. Hitting the ground, or even water, at full flight speed would be quite dangerous. Before touching down, they must decrease their speed in order to land safely. Both bats and birds have mastered the skill of landing, but these two types of flyers go about it quite differently.

    In the past it was believed that, in terms of flying mechanics, there was little difference between bats and birds. This belief was based only on assumption, however, because for years nobody had actually studied in detail how bats move their wings. In recent years, though, researchers have discovered a number of interesting facts about bat flight. Bats are built differently from birds, and their wings are made up of both their front and hind limbs (肢体). This makes coordinating (协调) their limbs more difficult for bats and, as a result, they are not very good at flying over longer distances. However, they are much better at the ability to adjust themselves: a bat can quickly change its direction of flight or completely reverse it, something a bird cannot easily do.

    Another interesting characteristic of bat flight is the way in which bats land-upside down! Unlike birds which touch down on the ground or on tree branches, bats can be observed flying around and then suddenly hanging upside down from an object overhead. One downside to this landing routine is that the bats often land with some force, which probably causes pain. However, not all bats hit their landing spots with the same speed and force; these will vary depending on the area where a bat species makes its home. For example, a cave bat, which regularly lives on a hard stone ceiling, is more careful about its landing preparation than a bat more accustomed to landing in leafy treetops.

    Garbage sorting has become a hot issue around China, especially after Shanghai began carrying out a regulation on July 1.

    Beijing, as a forerunner in environmental protection, has thus been expected to follow suit. The capital of the country has long been campaigning for sorting and recycling household waste, as part of its environmental drive for sustainable growth, local media reported.

    The current regulation gives garbage sorting responsibilities to government departments, property management groups and other organizations. It also gives rules for companies, outlining how they're responsible for waste collection, transportation and treatment. Only individuals are not subject to responsibilities.

    The long-awaited revision will soon change the situation, "Taking out the trash without sorting it properly will be illegal," said Sun Xinjun, director of the Beijing Commission of Urban Management. In Shanghai, violators are now fined up to 200 yuan ($30)for trash-sorting violations. The maximum fine in Beijing will not be less than that, he said.

    The Beijing city government first set out to promote garbage sorting in 2009. Authorities have since called on citizens to sort their household waste into four types-recyclable waste, kitchen trash, dangerous waste and others-and leave it in a corresponding dustbin or trash can. Blue-colored dustbins signify items within are recyclable, green represents kitchen trash, red corresponds to dangerous materials and grey to other waste.

    To promote the awareness of garbage sorting and expand the base of participants, authorities have employed workers to help residents on the spot. With intelligent devices, those who throw in recyclable waste at given sites will be rewarded with bonus points, which can be used to buy daily goods. At some communities, there are no color-coded dustbins. Instead, a scheduled garbage collection service is offered to help improve the environment. In other communities, workers offer a door-to-door service to collect recyclables or kitchen waste.

    Beijing Environmental Sanitation Engineering Group has been promoting new garbage sorting facilities such as recycling cabinets and smart kitchen waste trash cans since 2016, Xinhua News Agency reported. Nearly 26,000 metric tons of household waste is generated across Beijing on a daily basis and 29 terminal garbage disposal facilities are working at full capacity. Nearly 9.3 million tons of household waste was processed in the city last year.