On plenty of drives with my mom through my childhood, she would suddenly pull over the car to examine a flower by the side of the road or rescue a beetle from tragedy while I, in my late teens and early twenties, sat impatiently in the car.

    Though Mother's Day follows Earth Day, for me, they have always been related to each other. My mom has been “green” since she became concerned about the environment. Part of this habit was born of thrift (节俭). Like her mother and her grandmother before her, mom saves glass jars, empty cheese containers and reuses her plastic bags.

    Mom creates a kind of harmonious relationship with wildlife in her yard. She knows to pick the apples on her trees a little early to avoid the bears and that if she leaves the bird feeders out at night, it is likely that they will be knocked down by a family of raccoons (浣熊). Spiders that make their way into the house and are caught in juice glasses will be set loose in the garden.

    I try to teach my children that looking out for the environment starts with being aware of the environment. On busy streets, we look for dandelions(蒲公英) to fly in the wind; we say hello to neighborhood cats and pick up plastic cups and paper bags. This teaching comes easily, I realize, because I was taught so well by example. Mom didn't need to lecture; she didn't need to beat a drum to change the world. She simply slowed down enough to enjoy living in it and with that joy came mercy and an instinct(直觉) for protection.

    I am slowing down and it isn't because of the weight of my nearly forty years on the planet, it is out of my concern for the planet itself. I've begun to save glass jars and reuse packing envelopes. I pause in my daily tasks to watch the squirrels race each other in the trees above my house.

    Last summer, in the company of my son and daughter, I planted tomatoes in my yard. With the heat of August around me, I ate the first while sitting on my low wall with dirt on my hands. Warm from the sun, it burst on my tongue with sweetness. I immediately wanted to share with my mom.

    Reading can be a social activity. Think of the people who belong to book groups. They choose books to read and then meet to discuss them. Now, the website BookCrossing.com turns the page on the traditional idea of a book group.

    Members go on the site and register the books they own and would like to share. BookCrossing provides an ID number to stick inside the book. Then the person leaves it in a public place, hoping that the book will have an adventure, traveling far and wide with each new reader who finds it.

    Bruce Pederson, the managing director of BookCrossing, says “The two things that change your life are the people you meet and books you read. BookCrossing combines both.”

    Members leave books on park benches and buses, in train stations and coffee shops. Whoever finds their book will go to the site and record where they found it.

    People who find a book can also leave a journal entry describing what they thought of it. E-mails are then sent to the BookCrossers to keep them updated about where their books have been found. Bruce Pederson says the idea is for people not to be selfish by keeping a book to gather dust on a shelf at home.

    BookCrossing is part of a trend among people who want to get back the “real” and not the virtual(虚拟). The site now has more than one million members in more than one hundred thirty-five countries.

    Robots make me nervous — especially the ones which seem to think for themselves. I was embarrassed to admit this till I heard that Bill Gates, the founder of Microsoft, felt the same way.

Gates said in an interview with the social networking and news website Reddit: "I am in the camp that is concerned about super intelligence. First the machines will do a lot of jobs for us and not be super intelligent. That should be positive if we manage well. A few decades after that though the intelligence is strong enough to be a concern."

    Well, maybe I don't have to worry about my computer and kitchen equipment yet. After I use them I can always pull the plug. But in the future, machines might find a way to prevent us from switching them off. There's a terrible thought!

    Maybe the problem with computers too clever for us is not that they are evil like some we've seen in sci-fi movies. What could put us in danger is that they might be too efficient. That's what philosopher Nick Bostrom from Oxford University believes. He says that machines are indifferent to humans and in pursuit of their own goals, the destruction of people might be just additional damage. Bostrom gives us an example: A machine which might have as its only goal to produce as many paperclips as possible might look at human bodies as extra material for paperclips and go after you. Because it is, well, a machine, it would not take pity on you.

    It's a good thing that American writer Isaac Asimov thought about how far robots can go and left us his three rules of robotics. They state that a robot may not hurt a human being or allow the human being to come to harm.

I'm glad my machines at home are "dumb". All my cleaner wants to take over is the carpet in my living room. Let's hope they don't create an appliance which wants to take over the world!

    Making friends is a skill like many other skills. It improves with practice. If you want to meet people and make friends，you must be willing to take some actions. You must first go where there are people. You won't make friends staying home alone. Join a club or a group. Talking with those who like the same things as you do is much easier. Or join someone in some activities. Many people are nervous when talking to new people. After all meeting strangers means facing the unknown. And it's human nature to feel a bit uncomfortable about the unknown. Most of our fears about dealing with new people come from doubts about ourselves. We imagine other people are judging us or finding us too tall or too short，too this or too that. But don't forget that they must be feeling the same way. Try to accept yourself as you are and try to put the other person at ease. You'll both feel more comfortable.

    Try to act self­confidently even if you don't feel that way. When you enter a room full of strangers，such as a new classroom，walk tall and straight，look directly at other people and smile.

    If you see someone you'd like to speak to，say something. Don't wait for the other person to start a conversation.

    Just meeting someone new does not mean that you will make friends with that  person—friendship is based on mutual liking and“give and take”. It takes time and effort to develop.

    On a recent spring morning. Susan Alexander, a retired government intelligence analyst, left her Maryland home, climbed into her Volkswagen Passat and drove about three miles to pick up two strangers. She battled rush-hour traffic on the Capital Beltway and George Washington Memorial Parkway before dropping them off at Reagan National Airport. She didn't earn a cent for her trouble, and that was the point.

    Alexander is a member of the Silver Spring Time Bank-one of more than 100 such exchanges around the world trying to build community by exchanging time credits for services instead of dollars and cents. "I have time," she said. "I like giving the gift of time to other people."

    In Alexander's case, passengers Mary and Al Liepold were grateful for the ride, but it wasn't charity. Mary, a retired writer and editor for nonprofit organizations, used time credits she banked for editing work and baking. Senior citizens who don't drive, the Liepolds cashed in their credits to catch a flight to Montreal for a five-day vacation.

    Without money changing hands or shifting between virtual accounts, the airport drop-off was more like a coffee party than a taxi ride. Driver and passengers chatted about projects they've completed for the time bank, and no one raised an eyebrow when Mary said she likes "to avoid the conventional economy."

    "The beauty of this is that you make friends," Mary Liepold said. "You don't just get services."

    The Silver Spring Time Bank formed in 2015 and has about 300 members, said co-founder Mary Murphy. Last year, she said, l,000 hours were exchanged for basic home repairs, dog walking, cooking and tailoring, among other services, without the exchange of money. "You get to save that money that you would have spent," she said. "You get to meet somebody else in your community and get to know that person. That's a bonus that's part of an exchange."

    A deal performed partly to make friends would seem to go against classical economics and one of Benjamin Franklin's most memorable sayings: "Time is money." To those at the forefront of modem time-banking, that is the appeal.

    When it comes to medical care, many patients and doctors believe "more is better." But what they do not realize is that overtreatment—too many scans, too many blood tests, too many procedures—may bring harm. Sometimes a test leads you down a path to more and more testing, some of which may be invasive, or to treatment for things that should be left alone.

    Terrence Power, for example, complained that after his wife learned she had Wegener's disease, an uncommon disorder of the immune system, they found it difficult to refuse testing recommended by her doctor. The doctor insisted on office visits every three weeks, even when she was feeling well. He frequently ordered blood tests and X－rays, and repeatedly referred her to specialists for even minor complaints. Even when tests came back negative, more were ordered, and she was hospitalized as prevention when she developed a cold. She had as many as 25 doctor visits during one six－month period. The couple was spending about $30,000 a year for her care.

    After several years of physical suffering and near financial ruin from the medical costs, the couple began questioning the treatment after discussing with other patients in online support groups. "It's a really hard thing to determine when they've crossed the line," Mr. Power said. "You think she's getting the best care in the world, but after a while you start to wonder: What is the purpose?" Mr. Power then spoke with his own primary care doctor, who advised him to find a new specialist to oversee Mrs. Power's care. Under the new doctor's care, the regular testing stopped and Mrs. Power's condition stabilized. Now she sees the doctor only four or five times a year.