Dolphins (海豚) live in a dark underwater world. It's often impossible to see each other or anything else around them, so sound plays an important role in their survival. To communicate with each other, dolphins produce all kinds of sounds.

    Only other dolphins understand what the sounds mean. Scientists haven't uncovered their secret communication, except for one kind of whistle. It might last less than a second, but this whistle is a big deal. Why? Because these whistles are actually names of dolphins — and every dolphin has one. Scientists call these sounds a “signature whistle.” When other dolphins hear the whistle, they know which dolphin is calling.

    Dolphins often hunt by themselves but still need to stay connected to the group. Since they can't always see each other, dolphins use their signature whistles to check in with other dolphins hundreds of yards away. “In coastal areas, dolphins exchange whistles even when they're a third of a mile apart,” says Greg Campbell, who studies animals. That means dolphins shout out to group members that might be nearly five football fields away.

    What's amazing is who names the baby dolphin. Not the mother. Not an auntie dolphin or another group member. Scientists believe the baby dolphin itself comes up with the signature whistle. Like human babies, a baby dolphin plays with sounds throughout its first year. While testing its sound skills, a baby dolphin is doing something amazing. It's creating or figuring out its signature whistle. How or why it chooses its signature whistle is not clear. Studies show that most of the time the signature whistle is nothing like its mother's or group members' whistles.

    When the baby dolphin is about a year old, its signature whistle is set. It repeats it often so the other dolphins learn to recognize it.

    Deciphering(破译) dolphin names is just the beginning of figuring out what dolphins communicate about. Do they chat about sharks? Discuss the tides? Maybe they even have a name for people. Someday scientists are to decipher the rest of dolphins' communication.

"Dad," I say one day …..take a trip. Why don't you fly and meet me?"

    My father had just reired……….. His job filled his day, his thought, his life. While he woke up and took a warm shower, I screamed under a freezing waterfall Peru. While he tied a tie and put on the same Swiss watch, I rowed a boat across Lake of the Ozarks.

    My father sees me drfting aimlessly, nothing to show for my 33 years but a passport full of funny stamps. He wants me to settle down, but now I want him to find an adventure.

    He agrees to travel with me through the national parks. We meet four weeks later in Rapid City.

" What is our first stop?" asks my father.

"What time is it?"

"Still don't have a watch?"

    Less than an hour away is Mount Rushmore. As he stares up at the four Presidents carved in granite(), his mouth and eyes open slowly, like those of little boy.

"Unbelievable," he says, "How was this done?"

    A film in the information center shows sculptor Gutzon Borglum devoted 14 years to the sculpture and then left the final touches to his son.

We stare up and I ask myself, Would I ever devote my life to anything?

No directions, …… I always used to hear those words in my father's voice. Now I hear them in my own.

    The next day we're at Yellowstone National Park, where we have a picnic.

"Did you ever travel with your dad? I ask.

"Only once," he says. " I never spoke much with my father. We loved each other—but never said it. Whatever he could give me, he gave.">

    The kast sebtebce—it's probably the same thing I's say about my father. And what I'd want my child to say about me.

In Glacier National Park, my father says, "I've never seen water so blue." I have, in several places of the world, I can keep traveling, I realize—— and maybe a regular job won't be as dull as I feared.

    Weeks after our trip, I call my father.

"The photos from the trip are wonderful," he says." We have got to take another trip like that sometime.

    I tell him I've learn decided to settle down, and I'm wearing a watch.

    Our local Community Youth Club is a very popular organization with young people in my town. I have been a member for four years now and I've taken part in a lot of interesting projects. These include fun activities such as holiday camps and discos. We have organized sports competitions and we even made a video.

    But it isn't all just enjoyment, we have also started doing social work to help people in our neighbourhood. We have organized activities for small children during the holidays. We have also formed a social support group to help young people stop smoking.

    We are particularly proud of the most recent group we have created. It organizes regular visits to the local old people's home. This idea came from a school visit to an old people' home. My class spent an afternoon at a home and everyone found the visit very rewarding.

    The old people at the home were very excited by our visit. They were very talkative(健谈的) and they told us their personal stories. During our visit, the home was filled with the sound of laughter. We sang songs and played games with the old people and had tea together. But we realized that life wasn't always easy. Some of them were in poor health and were very unhappy. They couldn't go outside the visits by children brought some sunshine into their lives.

    Many young people like me do not live with our grandparents and we have very little contact with elderly people. As a result, many young people don't know what they are like and we have a lot of wrong ideas about them. We have little or no idea of the kind of lives they lead in their homes. After this visit, my friends and I decided we should do something to help improve the quality of their lives.

    Since the creation of our visiting group, over twenty volunteers(志愿者) have joined us. Up to now, we have organized three group evenings and a concert. But it is the individual(单独的) visits which are the most important. Club members regularly visit old people and everyone finds the experience rich and rewarding.

    The human-caused rise in CO₂ hasn't yet reached its full warming effect, owing to the considerable delay in its impact on ocean temperature. There is still another 0.5^oC of so of warming to occur over the coming decades based on the current concentrations（浓度）of CO₂ in the atmosphere, and far more warming beyond that if CO₂ concentrations continue to rise greatly with the business-as-usual burning of fossil oil. To improve the situation, the world needs to shift firmly from coal, oil and gas to renewable energy by around 2050 and from cutting down trees to planting trees and restoring degraded lands.

    So why do human begins keep dashing in a stupid way ahead, toward certain tragedy?

    The main reason is that our political institutions and giant corporations intentionally ignore the rising dangers and damage.   ①    Managing a major company is about maximizing shareholder value, not about telling the truth or avoiding great harm to the planet. Profit -seeking investors own the major media, or at least influence them through their advertising purchases. Thus, a small yet very powerful group keeps the fossil-fuel-based energy system at growing dangers to the rest of humanity today and in the future.

    We need a new kind of politics that starts with a clear goal: environmental safety for the planet's people, by fulfilling the Paris agreement, protecting biodiversity, and cutting pollution, which kills millions each years.   ②    The new politics will listen to scientific and technological experts, not self-interested business leaders and politicians.

       ③    Such a politics is possible. In fact, the public longs for it. A large majority of the American people,for example, want to fight global warming, stay in the Paris climate agreement, and support renewable（可更新的）energy. Yet, as long as a narrow and ignorant elite（精英）judges Americans and the rest of human beings to wander aimlessly in the political desert, the more likely it is that we will end up in a wasteland from which there will be no escape.  ④   

    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, but truly can't 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.

    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,

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

On a recent Wednesday, archaeologists announced a groundbreaking discovery that challenges our understanding of early human capabilities. They have unearthed what is believed to be the oldest wooden structure ever found, dating back nearly half a million years. This discovery at Kalambo Falls in northern Zambia, near the border with Tanzania, suggests that our ancestors were more technologically advanced than previously thought.

The wooden structure, which is exceptionally well-preserved, dates back at least 476,000 years. This timeline predates the emergence of Homo sapiens, as detailed in a study published in the journal Nature. The wood shows evidence of having been cut and shaped using stone tools, indicating a level of craftsmanship that was not previously attributed to these early humans.

The structure, which is thought to have functioned as a walkway or platform elevated above the seasonally wet ground, demonstrates a purposeful construction technique. A collection of wooden tools, including a wedge and a digging stick, were also found at the site, further supporting the idea of a developed woodworking tradition.

Larry Barham, an archaeologist at the University of Liverpool and the lead author of the study, described the structure as involving "the intentional shaping of two trees to create a framework of two interlocking supports." A notch was cut into one log, and another tree was shaped to fit through this notch, providing stability to the structure.

The use of wood by early humans was already known, but it was typically associated with basic tasks such as starting fires or hunting. However, the discovery at Kalambo Falls indicates a more sophisticated application of woodworking skills. Barham explained, "The structure involves the intentional shaping of two trees to create a framework of two interlocking supports," which required a level of planning and execution that suggests a higher cognitive ability.

The preservation of the wooden structure is remarkable, given that wood typically decays over time, leaving little trace for archaeologists to study. The high water levels at Kalambo Falls are believed to have played a crucial role in preserving the structure for centuries.

These findings from Kalambo Falls not only provide evidence of an early human ability to manipulate their environment but also suggest a more complex cognitive capacity among these early humans than what has been inferred from stone tools alone. Barham concluded, "The finds from Kalambo Falls indicate that these earlier humans, like Homo sapiens, had the capacity to alter their surroundings, creating a built environment." This discovery underscores the need to reassess our understanding of early human technological and cognitive development.