Social change is more likely to occur in societies where there is a mixture of different kinds of people than in societies where people are similar in many ways. The simple reason for this is that there are more different ways of looking at things present in the first kind of society. There are more ideas, more disagreements in interest, and more groups and organizations with different beliefs. In addition, there is usually a greater worldly interest and greater tolerance in mixed societies. All these factors tend to promote social change by opening more areas of life to decision. In a society where people are quite similar in many ways, there are fewer occasions for people to see the need or the opportunity for change because everything seems to be the same. And although conditions may not be satisfactory, they are at least conventional and generally agreed.

    Within a society, social change is also likely to occur more frequently and more readily in the material aspects of the culture than in the non-material, for example, in technology rather than in values; in what has been learned later in life rather than what was learned early; in the less basic and less emotional aspects of society-than in their opposites; in the simple elements rather than in the complex ones; in form rather than in substance; and in elements that are acceptable to the culture rather than in strange elements.

    Furthermore, social change is easier if it is gradual. This is one reason why change has not come more quickly to Black Americans as compared to other American minorities, because of the sharp difference in appearance between them and white people.

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    Low-Cost Gifts for Mother's Day

    Gift No. 1

    Offer to be your mother's health friend. Promise to be there for any and all doctor's visits whether a disease or a regular medical check -up. Most mothers always say no need, another set of eyes and ears is always a good idea at a doctor's visit. The best part? This one is free.

    Gift No. 2

    Help your mother organize al1 of her medical records, which include the test results and medical information. Put them all in one place. Be sure to make a list of all of her medicines and what times she takes them. “Having all this information in one place could end up saving your mother's life,” Dr. Marie Savard said.

    Gift No. 3

    Enough sleep is connected to general health conditions. “Buy your mother cotton sheets and comfortable pillows to encourage better sleep.” Savard said. “We know that good sleep is very important to our health.”

    Gift No. 4

    Some gift companies such as Presents for Purpose allow you to pay it forward this Mother's Day by picking gifts in which 10 percent of the price you pay goes to a charity (慈善机构).Gift givers can choose from a wide variety of useful but inexpensive things many of which are “green”—and then choose a meaningful charity from a list. When your mother gets the gift, she will be told that she has helped the chosen charity.

    In Western countries people have been using the installment plan since the first half of the twentieth century. Today, a large number of families in Great Britain buy furniture, household goods and cars by installments In the U. S. A, the figure is much higher than in Great Britain, and people there spend over 10 percent of their income on the installment plan.

    The price of an article bought on installments is always higher than the price that would be paid by cash. There is a charge for interest. The buyer pays one quarter or one third of the price as a down payment when the goods are delivered to him. He then makes regular payments, weekly or monthly, until the full price is paid up. The legal ownership of the goods remains with the seller until the final payment has been made.

    Installment buying has advantages and disadvantages. It can help couples with small incomes to furnish their homes and star housekeeping. It increases the demand for goods, and in this way helps business and employment. There is, however, the danger that when business is bad, installment buying may end suddenly, making business much worse. This may result in a great increase in unemployment. If the people on the installment plan lose their jobs, they will probably not be able to make their payments. If great numbers of people are not able to pay their installment debts, there is a possibility that businessmen cannot collect their debts and will therefore lose money. If businessmen lose money or fail to make a satisfactory profit, it becomes more likely to have a depression. This is why, in some countries,the government controls the installment plan by fixing the amount of the down payment and installments to discourage people from buying more than they can pay for on the installment plan.

    TRAIL SAFE! is a unique safety training program designed specifically for National Park Service (NPS) Trail Volunteers, but is useful to everyone! It's based upon NPS Operational Leadership Training, where the human factor of safety is explored. TRAIL SAFE! captures (捕捉) the core learning objectives of the 16-hour Operational Leadership course while allowing volunteers to learn from their own homes online.

    The TRAIL SAFE! series includes eight video lessons, each ranging in length from 18 to 40 minutes long. Watch them over the course of multiple days, or "binge watch" the entire series in three hours—it's up to you—but please watch them in order from Lesson 1 through Lesson 8. After viewing the lessons, send your training verification (验证) emails to register your participation. When you have viewed and registered for all eight individual lessons, each participant will receive a TRAIL SAFE! pin and a SPE/GAR card in the mail for use in the field. Thank you for helping to make Sleeping Bear Dunes one of the safest work environments for NPS Trail Volunteers like yourself.

    Ready to start?

    Click on this link to access all TRAIL SAFE! videos: https://www.nps.gov/iatr/trail-safe.htm

    If you require Audio Descriptive versions of TRAIL SAFE! the link to those videos is also available on the Ice Age Trail site.

    Record your participation

    In order to receive credits for your participation, please fill in your answers to the following questions and email to: Matthew mohrmannps.gov.

    Which video lesson did you just complete viewing?

    Name of the Trail where you volunteer.

    Your name and full mailing address, so we may send your course completion materials to you.

    Names and addresses of others if you are viewing this lesson in a group setting.

    Optional: Please let us know any comments or suggestions you have about this lesson.

    Upon registering your completion for the entire eight lesson series, you'll receive your TRAIL SAFE! pin and risk assessment card via mail.

When we hold our breath and go underwater, we'll soon be unable to stand it. {#blank#}1{#/blank#} However, there's little chance of catching up with the Sama-Bajau, who can stay underwater with a single breath for quite a long time. 

Sama-Bajau is a collective term（集合术语）that refers to several closely related native peoples. The Bajau live on long houseboats or small wooden houses that are built on the sea, close to the shore in Southeast Asia. {#blank#}2{#/blank#}

 As they make their living primarily from fishing, they have become exper t free divers（自由潜水者）. Bajau divers have the longest daily diving time without breathing among allhumans. {#blank#}3{#/blank#} In their free time, the kids help around the house or play on the beach. 

It appears that centuries of free diving have scientifically distinguished the Sama-Bajau. According to research, the Bajau's spleens（脾脏）are much larger than the average people's on land. {#blank#}4{#/blank#} Besides, the Bajau have also developed excellent underwater vision. 

{#blank#}5{#/blank#} The main cause is massive fishing, which has made it increasingly difficult for the Bajau to make a living and rely on fishing alone. As a consequence, more and more people are leaving the seas, and apparently, it's only a matter of time before the Bajau and their amazing qualities disappear. 

A. Larger spleens can have some weaknesses. 

B. Therefore, many older divers are hard of hearing. 

C. The difference makes the Bajau quite able to dive underwater. 

D. They only go ashore to trade or seek shelter during sea storms. 

E. Bajau children master swimming and diving skills at an early age. 

F. The existence of this special group of people is threatened nowadays. 

G. With free diving training, we can increase the time underwater by a few minutes. 

Have you promised that your are going to get healthier? Maybe you want to lose weight, get stronger and have more energy. Maybe you are under the doctor's orders to eat right and take exercise more. Well, those all sound great. But with so many choices, it can be hard to get started. {#blank#}1{#/blank#} .

Eat right. Healthy eating is harder than before. Now many supermarkets or restaurants are packed with unhealthy choices that cause weight gain and weaken energy. Over time, making poor food choices can cause illness. But you don't have to be concerned about it. {#blank#}2{#/blank#} Cut out the junk food.

Keep healthy. {#blank#}3{#/blank#}. So take exercise at once. Once you get started, you will be more likely to stick to it. Reduce stress. In the US, 77% of people often experience physical stress. {#blank#}4{#/blank#}You can manage stress by taking exercise, getting enough rest and cleaning bad relationships from your life.

{#blank#}5{#/blank#}. Sure, some people are naturally happier than others. But there are things you can consciously do to be happier. And guess what they are all free. So if you want to be happier, there are a few things to do, for example, express thanks, help others ,or how to meditate.

A. Sleep well.

B. Choose happiness.

C. So here are healthy tips that you can follow.

D. Eat natural and organic foods as often as possible.

E. That is not a group you want to be a part of.

F. So tell someone you love how you feel about them.

G. People who often take exercise are generally happier and healthier than people who don't.