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.

    Today, I had the good fortune to join the students from East Silver Spring Elementary School in Maryland as they walked and biked to school in celebration of International Walk to School Day. I want to thank Principal Morrow and the entire ESS community for welcoming me so enthusiastically.

    Walk to School Day is a great opportunity for me to spend time with parents, kids, and teachers and to present our Safe Routes to School program and the First Lady Michelle Obama's Let's Move initiative（倡议）.

    As a father, grandfather and former schoolteacher, I know how important it is that we provide students with safe choice to get to school while promoting exercise and healthy lifestyles. That's why I've embraced the Safe Routes to School program so wholeheartedly since I became Secretary of Transportation.

    You know, we're looking at an increasingly sedentary（久坐的）generation of children. One out of every three kids in America is now overweight. And I admire the First Lady's effort to end this within a generation. Safe Routes to School is a natural partner for Let's Move. For more than 10 years, Safe Routes to School has been making it easier for students to walk and bike from home to school. And ESS, where I walked today, is one of the earliest schools to participate.

    We know this program has been enormously effective because of the steady increase in the number of kids walking or biking to school. And as we made our way down the street this morning I was reminded yet again of this program's extraordinary work.

    Look, walking and biking to school is good for students' health. It's good for the environment. And it's good for the entire community's quality of life.

Everybody wins when kids take Safe Routes to School.

    A bicycle may be seen by most people as just another vehicle (交通工具), but for many Londoners, cycling is a way of life. According to an official UK government survey in 2017, about 570,000 bike journeys are made every day in London. In fact, almost half of the vehicles that pass over London Bridge each day are bikes.

    London introduced a public bike-sharing system in 2010. "There can be no doubt that our trusty bicycles have changed the way people get around our great city," Johnson told the Guardian in 2015.

    In London, bikes are used for more than just taking short trips to and from the subway. No matter where you want to go in the city, taking a bike is usually the quickest and easiest choice.

    And it's not just shared bikes that the government is encouraging people to ride. In many companies across the UK, the UK government's Cycle to Work scheme (骑行倡议) allows employees to buy a brand new bike without having to pay any tax (税). This means that it's common to see many people cycling to and from work, and some employers even provide workplace showers and lockers (储物柜) for their workers. More importantly, a cycle-friendly boss may let you off for being late if you rode a bike to work.

    Not only is it great for the environment and our body, cycling is also good for the mind. According to National Geographic Magazine, "Bike riding can improve people's happiness."

    Making employees feel happy and healthy at work is good for many businesses. But it isn't always an easy thing. A study suggests that only 33% of the U. S. employees consider themselves fully engaged （投身于）in work, while 16% are greatly disengaged, and 51% are just showing up.

    But there is an exception. When it comes to employee engagement, it seems that employees in small companies are doing better. According to the same research, the largest U. S. companies are at the lowest levels of engagement, while companies with fewer than 25 employees are at the highest. And in one recent report, 75% of small business workers surveyed said they were "very" or "extremely" satisfied with their role as a small company employee.

    Unlike big companies, small companies are often short of resources but the employees can get more surprises there. Small companies offer excellent career opportunities to their employees. The bosses often know their staff very well and understand their personal needs. Employees of small companies are more likely to receive free meals, paid leave, and they can even bring their pets to work.

    But of course, there are many other draws in small businesses. One of the top draws is flexible scheduling (弹性工时). Another is being able to really see the fruits of one's labor. Besides, non-cash award is also a big draw. This could be something small that reflects employees' interests and lifestyles.

    While a parental leave might lead to some financial problems, small companies may do something to improve it. "It may be impossible for a five-person team to be reduced to four for six months," writes Camillia Velasquez, head of HR management platform, Justworks. "But it could be possible to allow new parents to take on reduced hours in a work-from-home environment." This kind of method has been realized in some small companies.

    Humans and many other mammals have unusually efficient internal temperature regulating systems that automatically maintain stable core body temperatures in cold winters and warm summers. In addition, people have developed cultural patterns and technologies that help them adjust to extremes of temperature and humidity (湿度).

    In very cold climates, there is a constant danger of developing hypothermia, which is a life-threatening drop in core body temperature to below normal levels. The normal temperature for humans is about 37.0℃. However, differences in persons and even the time of day can cause it to be as much as 6℃ higher or lower in healthy individuals. It is also normal for core body temperature to be lower in elderly people. Hypothermia begins to occur when the core body temperature drops to 34.4℃. Below 29.4℃, the body cools more rapidly because its natural temperature regulating system usually fails. The rapid decline in core body temperature is likely to result in death. However, there have been rare cases in which people have been saved after their temperatures had dropped to 13.9-15.6℃. This happened in 1999 to a Swedish woman who was trapped under an ice sheet in freezing water for 80 minutes. She was found unconscious, not breathing, and her heart had stopped beating, yet she was eventually saved despite the fact that her temperature had dropped to 13.7℃.

    In extremely hot climates or as a result of uncontrollable infections, core body temperatures can rise to equally dangerous levels. This is hyperthermia. Life-threatening hyperthermia typically starts in humans when their temperatures rise to 40.6-41.7℃. Only a few days at this extraordinarily high temperature level is likely to result in the worsening of internal organs and death.

Hearing aids usually bring to mind images of ugly, ineffective devices mainly worn by the elderly. But this ill repute (恶名) is quickly changing, as they've recently taken a turn thanks to two innovators, Dr. Marco Vietor and Paul Crusius, who now lead the fastest-growing hearing aid company in the world-hear. com.

Hear. com's years of research led to the development of two game-changing hearing aids-the Silk and Styletto. These impressive devices pack cutting-edge (尖端的) technology in designs that are practically invisible. They also use a unique way that has been clinically (临床地) proven to deliver better-than-normal hearing so you can clearly understand speech in any environment. With additional features like Bluetooth and rechargeability, today's hearing aids are attracting even younger customers skilled in tech.

But hear. com knows it's not just about tech and design. They've put an enormous effort into the entire experience to make hearing care more accessible and more affordable. "Everyone should be able to hear well to live well," Crusius says. "And it's very individual. Each person's hearing loss is different and requires a personalized approach to find the best solution."

"We hear with our brains, not our ears. And it takes at least 30 days for our brain to adjust and relearn how to hear again with new hearing aids," Dr. Vietor says. "To guarantee your best outcome with hearing aids, we developed the industry's first 30-day program, Hearing Success Program, so customers have that extra level of care and knowledge to succeed."

And it's working. Hear. com has now helped more than 100,000 customers improve their hearing. Their A+ rating with the Better Business Bureau and 5-star rating on the customer review platform, Trustpilot, speaks for itself.

Hear. com's "customer first" approach also helps drive the company's success, encouraging employees to act like owners and put customers first. "We're investing heavily in shaping our company culture," Crusius says. "Individuals who work at hear. com say they are here to do more than a job. They're helping change lives all around the world."