Both instructors and learners can get benefits from the following learning strategies as long as they are properly made use of in language learning.

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    The information presented in this section focuses on specific conversation, discussion, or presentation skills. The activities are generally self-explanatory, with students expressing opinions, making decisions, solving problems, planning presentations, and so on. Engaged in these activities, students have the possibility of communicating with each other in class. This section also includes lists of expressions used to illustrate different language functions, such as agreeing, disagreeing, and asking for clarity in order to help students expand their knowledge of English.

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    In a speaking or listening course, students' anxieties can affect their learning. For this reason, it is important to establish a friendly, relaxed classroom environment. It may help students 10 think of the classroom as a laboratory where they can experiment and take risks with the language. In such circumstances, students should realize that errors are a natural and expected part of learning a language. In addition, one of the goals of this pan is to encourage students to examine their awn opinions and values while at the same time showing respect for the opinions and values of others.

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    Many of the activities in this section involve the students' cooperating work in class. Generally, such an activity taken up by four members seem to work the best. Groups of three or five members may also be effective, depending on the activity. The first unit includes guidelines for organizing group work, with students taking on the following roles: leader, reader, summarizer, reporter, and observer (if necessary). Organizing all activities in this way makes the course truly learner-centered since students must take fall responsibility for carrying out each activity. As for seating, group members should arrange their seats or chairs in a small circle to encourage interaction.

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    Being a teacher, in the course of group activities, you should circulate from group to group, which helps ensure that students are on task and are using English. While you should not participate in pair or group activities, you need to stay involved in what the students are doing. One important reason to circulate during activities is to keep track of the kinds of problems students have, such as grammatical accuracy, fluency, word choice, pronunciation and intonation discussion strategies, etc. However, it is generally not effective to correct students' errors when they arc involved in an activity. The most practical way to deal with communication problems is to make notes of what you observe as you arc circulating. You can then use this information to provide feedback after the activity or to develop future lessons.

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    At the beginning of the course, when they need to build up their confidence, students benefit most from encouragement and positive comment. If possible, you'd rather not grade the students fust few efforts at speaking in a group or to the class. Many students suffer such anxiety in speaking situations that any criticism at this stage can have the opposite effects. Commenting on students' work does not necessarily mean grading them on the scene. Even if the programs requires formal grades, you should try to put off assigning grades until later in the term.

    An autonomous vehicle designed for making local commerce deliveries was unveiled by Nuro. The vehicle is about the height of an SW but far narrower than a typical car. The electric car features four exterior compartments (暗格) — two on each side — to hold separate deliveries. Each compartment can be tailored to a specific use, such as cooking a pizza or refrigerating a package.

    “We can use self-driving technology to deliver anything, anytime, anywhere for basically all local goods and services,” Nuro co-founder Dave Ferguson said. “Consumers used to be okay with two-week paid shipping. It became two-week free delivery, followed by one week, two days, and the same day. Now same-day delivery isn't fast enough for some customers.”

    Nuro isn't alone in building robots for local commerce deliveries. Earlier this month, Toyota, a Japanese car company, unveiled a concept vehicle that could be used for package delivery. A handful of startups — including Starship Technologies, Marble and Dispatch — are testing small robots for deliveries on sidewalks.

    Nuro's vehicle will likely face legal hurdles. Fully autonomous vehicles without a test driver aren't legal in California today, and many companies have shifted testing to states where regulators are more welcoming of autonomous vehicles, such as Arizona.

    Nuro expects to face fewer challenges because it doesn't carry passengers. Nuro's narrow size may also be helpful when navigating streets and avoiding pedestrians. The vehicle isn't equipped with any special features to communicate with pedestrians or other road users. Some companies have tested and patented solutions such as digital screens that signal the car's next move. Ferguson said his team conducted studies and found that such techniques could confuse people. Nuro believes it's better to make sure the car performs predictably, so that human drivers know what to expect from it.

    “We feel by creating this new technology that's going to enable this last mile delivery, we're going to be creating new markets and doing things that previously weren't possible,” Ferguson said. “This is not swapping out Jobs with robots. It's creating new markets. There will definitely be new employment opportunities.”

    Most people who fly on passenger planes in the United States do not lose their luggage. Even if the luggage is lost, usually it is only delayed. Most “lost” luggage is found in a few days. Airlines search for the owners of unclaimed(未认领的) bags for up to three months. But when the owners cannot be found or the bags are not claimed, they are sold to a store in the small city of Scottsboro, in the southern state of Alabama.

    About one-half of one percent of all luggage passing through US airports is unclaimed. Many of the missing bags, and what is in them, are sold at the Unclaimed Baggage Center. Seven thousand items arrive at the store every day. Tom Barnes, who was shopping at the store said, “I can go into any of the large shopping centers, like the international malls. I can walk through there for an hour and come out with three items. But I come into this store, and then I come out with my car full of stuff.”

    Brenda Cantrell, who works at the store, said, “The Unclaimed Baggage Center is the only store in America that buys and resells unclaimed baggage from the airline industry. You would be surprised at all the jackets, eyeglasses, neck pillows, blankets, laptops, Kindles, iPads, and you know, all kinds of expensive electronics.”

    The store says it once sold a container for flowers for $80 that was found to be worth $18,000. And it says a painting it sold for $25 was later found to be worth $25,000.

    The store buys the luggage from the airlines. It does not examine the things inside them before buying them. Only about half of the items in the bags are suitable for sale at the store.

    Some people say it is not fair to the owners of the lost passage to sell their goods. Customer Daniel Martin is not one of them, saying, “I feel the airport may try to find the people that lose the things. If they've tried and they can't get a hold of them, it's better than throwing them away or just letting them rot in a warehouse somewhere.”

    America is a mobile society. Friendships between Americans can be close and real, yet disappear soon if situations change. Neither side feels hurt by this. Both may exchange Christmas greetings for a year or two, perhaps a few letters for a while — then no more. If the same two people meet again by chance, even years later, they pick up the friendship. This can be quite difficult for us Chinese to understand, because friendships between us flower more slowly but then may become lifelong feelings, extending (延伸) sometimes deeply into both families.

    Americans are ready to receive us foreigners at their homes, share their holidays, and their home life. They will enjoy welcoming us and be pleased if we accept their hospitality (好客) easily.

    Another difficult point for us Chinese to understand Americans is that although they include us warmly in their personal everyday lives, they don't show their politeness to us if it requires a great deal of time. This is usually the opposite of the practice in our country where we may be generous with our time. Sometimes, we, as hosts, will appear at airports even in the middle of the night to meet a friend. We may take days off to act as guides to our foreign friends. The Americans, however, express their welcome usually at homes, but truly can not manage the time to do a great deal with a visitor outside their daily routine. They will probably expect us to get ourselves from the airport to our own hotel by bus. And they expect that we will phone them from there. Once we arrive at their homes, the welcome will be full, warm and real. We will find ourselves treated hospitably.

    For the Americans, it is often considered friendly to invite a friend to their homes than to go to restaurants, except for purely business matters. So accept their hospitality at home!

    The world we live in gets more mechanized every year. Some countries which were mainly agricultural a hundred years ago have now become industrial. New factories and towns have been built on good agricultural land. There are now fewer farms to serve a much greater population, so these farms must be more efficient in order to produce as much food as possible. There is no place in the modern agricultural world for the inefficient farmer. Unfortunately, many of the picturesque aspects of farming are disappearing in the search for efficiency. The more tractors are used, the fewer horses are needed. Everyone agrees that horses are far more pleasant to look at than tractors. But they are less efficient. Cows are usually milked by machinery nowadays, and even pigs are fed automatically. There is not much art or poetry on the modern farm, and the old traditional idea of a farm as a slow, peaceful, romantic place is totally wrong nowadays.

    The modern farmer has to be a mechanic, a scientist, an accountant and a gambler. The more mechanized farming becomes, the more expert the farmer has to be. He must understand what machinery is necessary for his kind of farm, and he must know how to use it efficiently. He must also understand the new technical advances in agriculture, and how to use chemical and synthetic products to improve his crops. The more workers a farmer employs, the more he must know about the problems of wages and taxes. As in any other industry, most modern farmers find it necessary to employ office staff to deal with these. But although he has more modern equipments and far more scientific aids than his grandfather had, the farmer is still dependent upon the weather. As he can never be sure what the weather will do, he must be prepared to take risks, and face the possibility of losing everything.

    Engineers in Upstate New York have invented a folded paper device that looks like a decorated art project. But don't be fooled. This is actually a paper-based battery. No, it doesn't look like any of those metal batteries running flashlights or smartphones. In these systems, the battery can be printed on a page. The battery's power consists of living bacteria.

    Paper electronics are simple to make and inexpensive, notes study leader Seokheun Choi, an engineer at Binghamton University. They need no electrical outlet to recharge. They just need more bacteria, which can be found everywhere — including dirty water.

"Most batteries use chemicals to generate electricity. Substituting bacteria can be an advantage," Choi says. "They are cheap and self-repairing." What paper-based batteries won't do is generate much power. They do, however create enough to run small devices in faraway or dangerous places — such as a battlefield. They might also find use in medicine. For instance, they might power tiny sensors, such as the types used to measure blood sugar.

This invention is based on an observation made more than a century ago — that microbes (微生物) produce electricity as they digest food. Scientists refer to the bio-batteries based on this principle as microbial fuel cells. A fuel cell generates electricity like a regular battery. But a regular battery stops producing electricity when its inner chemical reactions stop. A fuel cell uses fuel that can be refilled. In this case, bacteria serve as the fuel. By refilling more microbes, as needed, scientists can keep these fuel cells running.

    Lab tests have shown that the new battery can produce a current. Now, Choi and his team are looking at ways to increase the power. They're studying different shapes and materials for the anode and cathode (正负极). They're also looking for the best ways to combine batteries for more power. The beauty of the paper devices is that you can simply fold them to connect them. And they surely will be a trend in the near future.