The United States has always been a country of many cultures. Before Europeans came to North America, many groups of Native Americans lived here. Different Native American groups had different cultures. The first Europeans in the United States were from England and Holland, but immigrants came from all European countries. Many people also immigrated from Asia and Africa. Sadly, many Africans were brought to the United States as slaves. Many immigrants come from Latin America too. Today, the United States has people from more cultures than ever.

    In the 19th century, people spoke of the United States as a “melting pot.” People thought that all immigrates should forget their native cultures and languages and become English-speaking Americans. They felt that people should assimilate-join American culture. However, not everyone wanted to assimilate completely. Many people tried to keep parts of their cultures, such as foods, customs, and languages. However, their children often forgot their parents' or grandparents' language. But most Americans, even those whose families have been here a long time, can tell the countries their relatives came from. And of course, new immigrants take great pride in their curare and language.

    For all of these reasons, melting pot is no longer a good way to describe the United States. Instead, people now call the United States a “salad bowl.” They say salad bowl because in a salad, you can still see all of the individual parts (lettuce, tomato, and so on), but all the different parts mixed together and begin to take on the flavor of one another.

    Humans have been keeping animals as pets for tens of thousands of years, but Dr Jean-Loup Rault, an animal scientist at the University of Melbourne in Australia, believes new companions are coming: robot pets.

    “Technology is moving very fast,” Rault told ABC News, “The Tamagotchi in the early 1990s was really the first robotic pet, and now Sony and other big companies have improved them a lot.”

    This may not sit well with pet lovers. After all, who would choose a plastic toy over a lovely puppy? But Rault argues that the robotic kind has a lot going for it: “You don't have to feed it, you don't have to walk it, it won't make a mess in your house, and you can go on a holiday without feeling guilty.” The technology also benefits those who are allergic to pets, short on space, or fearful of real animals.

    It's not clear whether robot pets can replace real ones. But studies do suggest that we can bond with these smart machines. People give their cars names and kids give their toy animals life stories. It's the same with robots. When Sony stopped its repair service for its robot dog Aibo in March 2014, owners in Japan held funerals.

    As an animal welfare researcher, Rault is concerned about how robotic pets could affect our attitudes towards live animals. “If we become used to a robotic companion that doesn't need food, water or exercises, perhaps it will change how humans care about other living beings,” he said.

    So are dogs and cats a thing of the past, as Rault predicts? For those who grew up with living and breathing pets, the mechanical kind might not do. But for our next generation who are in constant touch with smart technology, a future in which lovely pets needn't have a heartbeat might not be a far-fetched dream.

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。

    Last year, I was on a plane with my friend, waiting for it to take off. The pilot's voice was heard throughout the plane: “Sorry for the delay, ladies and gentlemen. Our engines don't work. We are going to jump-start them. Once we get them going, we'll get up in the air and see what happens.”

    That was all he said. “See what happens? Shouldn't we have had a better plan than that?” At that point, I could only laugh nervously. One woman started crying: “Oh, no! We are going to crash!” There are sighs of desperation and anxiety, and we hadn't even taken off yet.

    The pilot even seemed unhappy. He told us one engine was working double time, and his plan was to get up in the air and see what happens! Then we did. We got up in the air, and what happened? Nothing. We arrived in Norfolk, and no sooner had the wheels touched down than applause burst out as everyone on the airplane breathed a sigh of relief.

    All too often, people stop achieving their goals just because they don't have a guaranteed result. But success will never be guaranteed. The best thing that you can do is to just get up in the air, and see what happens.

    If your aim is to build a business, then get up in the air and see what happens! Don't give yourself all the reasons why you can't. Do not wait until you have everything you need. You never will.

    If your goal is to start a friendship, say “Hello”, get up in the air and see what happens! The results could be very rewarding. If your goal is to learn a new skill, get up in the air and see what happens! It might not be as difficult as you think. It could be fun!

    Sitting on the peaceful coast of Galapagos Islands. Ecuador, watching the sun move quietly into the sea, you shouldn't forget that Charles Darwin (1809-1882) arrived here in 1835. He stayed on the islands for five weeks, observing various animals. This finally inspired (启发) his famous work, On the Origin of Species. You can certainly follow Darwin's footsteps and enjoy a trip from four to seven days to the islands. The islands are certainly a paradise (天堂) for wildlife, as there are no natural killers on the islands and the number of boats and visitors is under government control. Though you cannot walk freely as Darwin did about 200 years ago, each day is as impressive as it could be. The most well-known animal of the Galapagos is the giant tortoise(巨型海龟), which can be seen moving slowly around the highlands of Sanra Cruz, the second largest island in the archipelago(群岛). Some of these creatures are so old that they might have been seen in their youth by Darwin himself. Despite strict control over activities and timing, your stay on the Galapagos will be remembered as a chain of incomparable pictures: diving with sea lions that swim and play within inches of you; feeling small sharks touch your feet as you swim; and, most magically, seeing a whale and her baby surface with a great breath of air. Travelling between the islands and observing the wildlife that so inspired Darwin, you will feel as though you are getting a special view of an untouched world. At night you will sleep on board the ship, leaving the wildlife in complete occupation of the islands, which are as undisturbed now as they have been since the beginning of time.

    When you cross deep water driving too fast, you risk splashing water up into the air box and having it get sucked into the internal engine, which is more common than you think. There are a few steps you should take to clear the water out before you try to start it:

    ⒈First, drain the fuel tank, fuel lines and the oil. While it's draining, put a fan on the wiring and dry it out. Remove and clean the carburetor (化油器).

    ⒉Take the plugs out of the engine and turn it over to force any water out. Water will come out with the oil. Add oil to the engine and turn it over again, without the plug in. Let it sit for a while, then observe the oil to tell if there's any water in it (it will look like a white milky substance if there is water mixed with the oil). If it's there, drain it again and start over until there is little or no white showing in the oil.

    ⒊Now re-install the spark plug, add gas, then try to start the engine. You should have a can of ether (乙醚) handy just in case it's stubborn, but don't use too much. If it starts, let it run for a few minutes without making it work faster.

    ⒋After it runs for several minutes, shut it off, drain the oil and change the filter(过滤网). Run it again for a few minutes then shut it off and checks again for milky colored oil. If you have none, you should be good to go.

    ⒌If you cannot start the engine, you may have already ruined it and you will probably need to seek a professional to repair it, or, more likely, you'll have to replace it.

Freshmen at Central Valley High in Ceres had a busy week of good deeds, tied to Pay It Forward Day, April 30, and an urge to show the world that teens can be awesome.

Kids in Success 101 spent first period making sandwiches for the homeless. The classes, taught by Natalie Rowell and Becky Lynch, got to hand 200 bagged sandwiches to the charity giving out the food. "They got to really see what an impact they had. It was inspiring and heartwarming," Rowell said. Besides, students also made blankets to send to soldiers, and created 45 flower arrangements for senior people at the Hale Aloha Home in Ceres. "They were nervous going into it. But when they saw how happy the elderly were, the reality of what they did really surfaced," Rowell said.

Rowell said she liked working with children. get to see how they learn. "It's different from how we learn, but we're kind of the same because they struggle in some of the subjects that we find hard as well."

Success 101 was tailor-made for students with that kind of insight. The first-period class includes study help, speakers on teen subjects and an overall focus on looking past high school, figuring out the steps to create their future. "Some kids need that little push. In this class, that's what we do, we give them that little push," Lynch added. "Success would be beneficial for all ninth-grade students. Since the start of the year, I really see a change in them."

Raquel Alfaro, a teen participant who worked with the younger kids, likes the Pay It Forward idea. "This helps us show adults, and also kids, that we're doing something different and that we're not as mean and selfish as they think we are," Alfaro said.