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.

The Square

    Jack Dorsey, the co-inventor of Twitter, is promoting his latest invention called the Square. The square is a small plug-in attachment to your mobile phone that allows you to receive credit card payments.

    The idea starting from Dorsey's friend Jim McKelvey who was unable to sell some glass work to a customer because he couldn't accept a particular card being used.

    Accepting credit card payments for something you're selling isn't always easy, especially if you are mobile like a tradesman, or delivery service at a trade show.

    This latest invention uses a small scanner that plugs into the audio input item on a mobile device. It reads information on a credit card when it is swiped(刷卡). The information is not stored on the device but sent over secure channels to banks. It basically makes any mobile phone a cash register for accepting card payments.

    As a payer, you receive a receipt via email that can be instantly accessed securely online. You can also use a text message to authorize payment in real time. Retailers can create a payer account for their customers which speeds the payment process. For example, a cardholder can assign a photo to their card so their photo will appear on the phone for visual identity confirmation. Mobile devices with touch screens will also allow you to sign for goods.

    There are no contracts, monthly fees, or hidden costs to accept card payments using Square and it is expected the plug-in attachment will also be free of charge.

    As with Twitter, it's expected that Dorsey will direct the company based upon feedback from users. Square Inc. has offices in San Francisco, Saint Louis and New York and is currently beta testing the invention with retailers in the United States.

    Mexico sites on an island plateau (高原) surrounded by volcanic peaks, which makes air quality a constant concern for people who live there.

    In April, the country took a decisive step toward improving air quality by enacting a temporary ban on private and Federal vehicles in the city. The rule forbids people from driving in the city one day each week and one Saturday each month. Electric vehicles, government service vehicles, public transport options and school buses are not included in the ban.

    Mexico City isn't the first urban center to be involved in car-free living. But the ban is more than an awareness-raiser. It was enacted with the direct aim of solving air pollution. In March, the city sank into a deep brown haze of smog when the pollution levels passed the 200 mark. The city ordered some 1.1m of the area's 4.7m cars off the streets and also offered free bus and subway rides.

    Mexico City's temporary vehicle ban raises questions about the best ways to improve urban air quality. India, whose citizens breathe some of the world's dirtiest air, has tried a variety of solutions. Earlier this year, the Indian government started a 4% sales tax on new-car purchases.

    Beijing also has experience with cleaning the air. The city introduced alternate-day rules in advance of the 2008 Olympic Games, which produced good results. And then there is the London congestion (拥挤) charge, introduced in 2003. The charge has had a measurable effect on air quality.

For now, Mexico City — named by the United Nations as the most polluted city on the planet in 1992 — can look forward to the start of the region's rainy season, when daily showers will help lo clean the air.

    To err is human. To blame the other guy is even more human.

    Common sense is not all that common.

    Why tell the truth when you can come up with a good excuse?

    These three popular misquotes (戏谑的引语) are meant to be jokes, and yet they tell us a lot about human nature. To err, or to make mistakes, is indeed a part of being human, but it seems that most people don't want to accept the responsibility for having made a mistake. They naturally look for someone else who could be responsible for the problem. Perhaps it is the natural thing to do. The original quote about human nature went like this: “To err is human, to forgive, divine (神圣的).” This saying mirrors an ideal: people should be forgiving of others' mistakes. Instead, we tend to do the opposite —— find someone else to pass the blame on to. However, taking responsibility for something that went wrong is a mark of great maturity.

    Common sense is what we call clear thought. Having common sense means having a good general plan that will make things work well, and it also means staying with the plan. Common sense tells you that you take an umbrella out into a rainstorm, but you leave the umbrella home when you hear a weather forecast for sunshine. Common sense does not seem to be common for large organizations, because there are so many things going on that one person cannot be in charge of everything. People say that in a large company, “the right hand does not know what the left hand is doing.”

    And what is wrong with a society that thinks that making up a good excuse is like creating a work of art? One of the common problems with making excuses is that people, especially young people, get the idea that it's okay not to be totally honest all the time. There is a corollary (直接推论) to that: if a good excuse is “good” even if it isn't honest, then where is the place of the truth?

    China officially informed the World Trade Organization on Tuesday that it will ban the import of 24 different types of solid waste by the end of this year as part of a campaign to deal with environmental pollution and protect people's health.

    In response to growing public concerns over the potential environmental and health danger caused by the increasing amounts of solid waste imported into the country for recycling and treatment, China passed a special law in 1995 to control imports of waste materials, such as plastics, slag from steelmaking, unsorted scrap paper and discarded textile materials.

    A year later, the country published a list for solid waste imports and began implementing a permit system to control the import volumes and types of waste imported.

    However, due to the lack of effective supervision(监管) and the failure of relevant departments to fulfill their duties, solid waste imports have not been effectively controlled.

    So far, China is the world's largest importer of solid waste. According to the Ministry of Environmental Protection, China imported 7.3 million metric tons of plastic waste worth $3.7 billion in 2016, accounting for 56 percent of global imports of solid waste.

    Correct recycling of solid waste materials is an important part of the global economy, and moderate imports of scrap plastic, scrap paper and scrap rubber products, such as vehicle tires, can to some extent, make up for China's shortage of various raw materials.

    However, the lack of supervision has resulted in the country's severe soil and environmental worsening.

    Given that China's continuing efforts to push for industrial transformation and upgrading have resulted in a noticeable decline in the demand for the materials recycled from solid waste imports. It is right for the country to restrict such imports for the sake of the environment and public health, and to better adapt to the changed industrial structure.

    Imagine a relay race. During this race, an athlete holds a stick as he runs a certain distance. Then he passes the stick to the next runner. That person runs faster, and then passes the stick to a third runner. Now imagine that the runners do not pass a stick. Instead they pass shiny silk, as well as gold, fruit, and glass. Imagine that the race does not move forward in just one direction. Instead the runners go back and forth along a road. They trade goods all along this route (路线) and at each end of it. Now imagine that the runners are businessmen. They lead caravans (商队) or lines of camels that carry things to sell. They travel on the ancient Silk Road to earn their living.

    The Silk Road was a complex trade network. It passed through thousands of cities and towns. It stretched from eastern China, across central Asia and the Middle east, to the Mediterranean Sea. Businessmen traveled on the Silk Road from about 200 B.C. to about 1300 A.D. Then sea travel began to offer new routes. Some people called the Silk Road the world's longest highway. However, the Silk Road included many routes--not just one smooth path. The routes ran through mountains and across deserts. They passed through an area that now includes 18 countries. The Silk Road had many dangers. These dangers ranged from hot sun and deep snow to thieves and wars. Only expert traders could survive.

    The Silk Road got its name from its most prized goods. People used silk as money. They could pay taxes or buy goods with it. Traders carried more than just silk, though. They had gold, silver, and glass from Europe. People in the Middle East and Asia wanted these things. Businessmen also took horses from flat, grassy areas in central Asia and brought them to China and other areas. The horses changed the way people farmed and ran their armies. Indian businessmen traded salt and rare, beautiful stones. Chinese merchants traded medicine and china. They also traded paper, which quickly replaced animal skins in the west. Businessmen carried apples from central Asia to Rome. The Chinese had learned to combine different trees to create new kinds of fruit. They taught this science to others, such as the Romans. The Romans began to grow apples for food. The Silk Road led to worldwide commerce 2,000 years before the World Wide Web.

    The people along the Silk Road did not share only goods. They also shared beliefs. Monks, priests, and other faith leaders taught their religions to others. The Silk Road created pathways for knowledge, diplomacy, and religion.