Amazon is breaking into physical retail in a new way. The online retail giant revealed a new kind of physical store concept in a video published on Monday.

    The store, called Amazon Go, doesn't work like a typical Walmart or supermarket. Instead, it's designed so that shoppers will use an app, also called Amazon Go, to automatically add the products that they plan to buy to a digital shopping cart by scanning a QR code(二维码). They can then walk out of the building without waiting in a checkout line because Amazon will charge their Amazon account and send them a receipt.

    The first Amazon Go store is located in Seattle, where Amazon is headquartered. For years, there have been rumors the e-commerce company would expand its dominance from digital to physical shopping. Amazon began experimenting with physical bookstores a year ago, but Amazon Go may mark its boldest bet on physical ones yet. By removing much of the staff needed to operate a store, Amazon keeps costs lower than traditional competitors. It's also in a strong position to bring together data on its customers' shopping habits online and offline to make better suggestions in all situations.

    However, Amazon's move deeper into physical retail shops comes in a sensitive political climate. The company could be perceived as being a threat to some of the 3.4 million Americans who work as cashiers, according to the Bureau of Labor Statistics. On the campaign trail, Donald Trump repeatedly criticized Amazon and its founder Jeff Bezos for “getting away with murder tax-wise” and having “a huge antitrust(反垄断) problem.” Will the President& shy; elect add “job killer” to the list of criticisms?

    Amazon's effort to launch a new kind of retail store predates(在……之前) the rise of Donald Trump. “Four years ago we asked ourselves: what if we could create a shopping experience with no lines and no checkout? Could we push the boundaries of computer vision and machine learning to create a store where customers could simply take what they want and go?” The company says on an informational page about Amazon Go. For now, Amazon is starting slow. The Amazon Go is only open to Amazon employees in our Beta program, and is scheduled to open to the public in early 2017.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

    Six people are talking about the newly-built garden on the roof of their building.

    Jasmine: I loved the idea when Wilber first told me about it. We had lots of meetings with our neighbors, trying to make them understand why it's good to build a garden on the roof. Now people love coming here, and we have made a lot of friends!

    Wilber: The whole thing wasn't easy at first. But Jasmine helped a lot. And she was really good at making people happy to donate (捐赠) money for the roof garden.

    David: My kids love going up there. They sit there watching butterflies and birds. The roof garden brings them closer to nature.

    Samuel: You want something green? Visit the park! It's only one block away! After the roof garden was built, small insects started flying into my room! And the kids leave mud on the stairs when they come down from the roof!

    Rosie: Our building is now cooler in the summer. My baby sleeps well even on hot summer days!

    Flora: Guess where these tomatoes are from! Not from the supermarket. They're from our roof! It's wonderful, isn't?

    Most dog owners feel that their dogs are their best friends. Almost everyone likes dogs because they try hard to please their owners. One of my favorite stories is about a dog who wanted the owner to please him. One of my friends has a large German shepherd(牧羊犬) named Jack. These dogs are often very intelligent (clever). Every Sunday afternoon, my friend takes Jack for a walk in the park. Jack likes these long walks very much.

    One Sunday afternoon, a young man came to visit my friend. He stayed a long time, and he talked and talked. Soon it was time for my friend to take Jack for his walk, but the visitor didn't leave. Jack became very worried about his walk in the park. He walked around the room several times and then sat down directly in front of the visitor and looked at him. But the visitor paid no attention. He continued talking. Finally, Jack couldn't stand(容忍) it any longer. He went out of the room and came back a few minutes later. He sat down again in front of the visitor, but this time he held the man's hat in his mouth.

    German shepherds aren't the only intelligent dogs. Another intelligent dog is a Seeing Eye dog. This is a special dog that helps blind people walk along the streets and do many other things. We call these dogs Seeing Eye dogs because they are the "eyes" of the blind people and they help them to "see". Seeing Eye dogs generally go to special schools for several years to learn to help blind people.

    People often say that there is nothing in the world that can be as great as a mother's love. Some mother expressions mean just that. The phrase "mother lode" comes from mining. It means the place where the largest amount of gold can be found. But now, the term "mother lode" means a rich supply of anything. For example, you might say, "She just graduated from college and struck the mother lode with her new job!"

    When we call something "the mother of all", this means it is the biggest or best of something. Here is an example: "We are going to throw the mother of all parties this weekend. So you have to come!"

    Naturally, the word "mother" can be used to mean to give birth, even to something you cannot touch, such as an idea or wisdom. The saying "necessity is the mother of invention" means that when people really need to do something, they will find a way to do it. And "experience is the mother of wisdom" means that people learn from what happens to them.

    You might think all expressions about mothers are sweet and loving. Not so. A boy who is "tied to his mother's apron strings(围裙带)" is controlled by his mother. We can also call him a "mama's boy". Both of these terms are even more insulting(侮辱人的) if you are talking about a man, not a young boy. It can be a huge mistake for a woman to marry a "mama's boy" who is still "tied to his mother's apron strings".

    A show about mothers would not be complete without talking about the very popular but mysterious "Mother Goose". The short poems and songs that "Mother Goose" wrote are a part of growing up in the United States. Real or not, you could say "Mother Goose" is the mother of all nursery rhyme(童谣) writers.

    A California family drives a car that could help protect the environment. When Jon and Sandy go to the store or to their daughters' soccer games, they drive in high-tech style. They drive a $1 million, fuel-cell-powered car. It may be the world's most expensive car and one of the most environmentally friendly cars. The FCX is the first fuel-cell-powered car to be used by a family anywhere in the world. The FCX uses hydrogen and oxygen for fuel. Car makers have been working to develop vehicles that are better for the environment. They are developing cars that use fuel other than gasoline.

    And then what is fuel cell technology? Fuel cell technology works by changing the chemicals hydrogen and oxygen into water. This process produces electricity, and water vapor which comes out of the exhaust pipe. Most cars release dangerous gases such as carbon monoxide and carbon dioxide. Many scientists say these gases are major contributors to global warming. “The FCX is driven just like any other vehicle on the road, but without the gases which pollute the environment,” scientists say. Fuel cell technology has been around since the 1800s, but scientists have yet been to perfect it. They say it may take years before the technology is ready for widespread use. Another earth-friendly car is already on the market. Hybrid cars use both gasoline and an electric motor. They are becoming more popular with customers because they cut pollution and improve fuel efficiency.

    Sometimes people add to what they say even when they don't talk. Gestures are the "silent language" of every culture. We point a finger or move another part of the body to show what we want to say. It is important to know the body language of every country or we may be misunderstood.

    In the USA, people greet each other with a handshake in a formal introduction. The handshake must be firm. If the handshake is weak, it is a sign of weakness or unfriendliness. Friends may place a hand on the other's arm or shoulder. Some people, usually women, greet a friend with a hug.

    Space is important to Americans. When two people talk to each other, they usually stand about two and a half feet away and at an angle (角度), so they are not facing each other directly. Americans get uncomfortable when a person stands too close. They will move back to have their space. If Americans touch another person by accident, they say, "Pardon me" or "Excuse me". Americans like to look at the other person in the eyes when they are talking. If you don't do so, it means you are bored, hiding something, or are not interested. But when you stare at someone, it is not polite.

    For Americans, thumbs-up means yes, very good, or well done. Thumbs-down means the opposite. To call a waiter, raise one hand to head level or above. To show you want the check, make a movement with your hands as if you are signing a piece of paper. It is all right to point at things but not at people with the hand and index finger (食指). Americans shake their index finger at children when they scold them and pat them on the head when they admire them.

    Learning a culture's body language is sometimes confusing. If you don't know what to do, the safest thing to do is to smile.