Grey clouds move as low as smoke over the treetops at Lolo Pass. The ground is white. The day is June 10.It has been snowing for the past four days in the Bitterroot Mountains.Wayne Fairchild is getting worried about our trek over the Lolo Trail-95 miles from Lolo Montana to Weippe in Idaho, across the roughest country in the West. Lewis and Clark were nearly defeated 200 years ago by snowstorms on the Lolo.Today Fairchild is nervously checking the weather reports.He has agreed to take me across the toughest,middle section of the trail.

    When Lewis climbed on top of Lemhi Pass,140 miles south of Missoula,on Aug.12,1805,he was astonished by what was in front of him;“high mountain chains still to the West of us with their tops partially covered with snow.”Nobody in what was then the US knew the Rocky Mountains existed,with peaks twice as high as anything in the Appalachians back East.

    Today their pathway through those mountains holds more attraction than any other ground over which they traveled,for its raw wilderness is an evidence to the character of two cultures:the explorers who braved its hardships and the Native Americans who prize and conserve the path as a sacred (神圣的)gift. It remains today the same condition as when Lewis and Clark walked it.

    The Lolo is passable only from July to mid-September.Our luck is holding with the weather,although the snow keeps getting deeper.As we climb to Indian Post Office,the highest point on the trail at 7,033 ft,we have covered 13 miles in soft snow,and we hardly have enough energy to make dinner.After a meal of chicken,I sit on a rock on top of the ridge (山脊）.There is no light visible in any direction,not even another campfire.For four days we do not see another human being.We are occupied with the things that mix fear with joy.In our imagination we have finally caught up with Lewis and Clark.

    Paying a higher price than usual for a ticket to see a film in 3D is the annoyance of many a cinema-goer's life.

    But there may be a benefit to doing so, as a study has found that 3D films exercise the brain and improve short-term functioning in a similar way to brain-training tests.

    The research found that people who watched a movie in 3D improved cognitive (认知) skills, compared to those who watched it in 2D.

    The research was led by neuroscientist(神经学家) Dr Patrick Fagan from Goldsmiths University in London. More than 100 people took part in the experiment, where participants watched Disney film Big Hero 6 in either standard format or RealD 3D.

    They also carried out a brain-training-style test before and after seeing a section from the film. The test covered memory, reaction times and cognitive function and the results were compared later.

    According to the research, which was carried out in partnership with science group Thrill Laboratory, participants experienced a 23 percent increase in cognitive processing, as well as an 11 percent increase in reaction times.

    Dr Fagan said that the results showed enough of an improvement in brain function to suggest that 3D could play a part in improving brain power in the future.

    "These findings are more significant than you might think," he said. "It is a fact that people are living longer and there is a noticeable decline in cognitive brain function in old age which can worsen future quality of life. There has never been a better time to look at ways to improve brain function. The initial results of this study show that 3D films may potentially play a role in slowing this decline."

    A second part of the experiment involved those watching the film being fitted with headsets that scanned brain activity and this too showed heightened (加强的) activity when watching 3D. According to the results, participants were seven percent more engaged with what they were watching, adding to argument that 3D movies are more like watching real-life—something Professor Brendan Walker from Thrill Laboratory agreed with.

    "As Professor Brendan Walker's test concluded, 3D films are more attractive and heighten the senses — this, in turn, makes the brain run at quicker speeds," Dr Fagan said.

    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.

With the clicking of walking sticks and determined steps, a long line of walking group along the winding road is a fantastic sight. Almost each of the walkers is using some kind of fitness tracker. A few Fitbits, some Xiaomi wrist bands (手环), a couple of phone apps and some other pedometers (计步器) — and all, they say, are counting their steps.

    Fitness trackers are in. Sales figures for 2016 released by Internet Data Center (IDC) indicated 25% market growth compared to the previous year, with Fitbit taking the lion's share, followed by the brand Xiaomi.

    However, the wearables market has had a rollercoaster ride in recent months. Jawbone, once a popular fitness tracker brand, announced that it is leaving the consumer market. Microsoft has removed its Fitness Band on its online store although it is still available on retail (零售) giant Amazon. Fitbit remains a key brand name at the heart of the fitness tracker revolution. But it is recently reported to be cutting down on workers, and its founder James Park said it experienced “softer than expected” sales recently.

    Counting steps is probably the most common use of wearable devices (可穿戴设备), but recently experts have questioned whether the golden goal of walking 10,000 steps a day is actually worthwhile, and a US study concluded that health trackers did not aid weight loss.

Analyst Ben Wood from CCS Insight used to wear a fitness tracker on either wrist. Now, however, his concern is about users'experience — these devices don't tell you anything new after a while. There are also battery problems and many of the older and cheaper varieties aren't waterproof (防水的).

    Children's books are everywhere. New ones, old ones, made-into-movie ones. It seems as if the children's publishing industry is developing rapidly. Here are some books every young child should have in their book diet.

    The Peter Rabbit books by Beatrix Potter

    It's best to have a copy of the original stories, with the original drawings done by Beatrix Potter herself. In The Tale of Peter Rabbit are the delightful tales of Peter Rabbit. Included in the series are also cute little stories about mice. These books have sweet stories that teach lessons.

The Cat in the Hat by Dr. Seuss

    Dr. Seuss is, of course, the master of children's literature. Dr. Seuss teaches children to play with language and have a good time reading. The pictures are wonderful and inspire lots of fun questions. Big kids will like re-reading Dr. Seuss along with their younger sisters and brothers.

Make Way for Ducklings by Robert McCloskey

    The story of Mr. and Mrs. Mallard is shown by simple pencil drawings that help children use their imaginations. The story explores the city of Boston as the Mallards look for a place to get their ducklings safely across the city. Jack, Kack, Lack, Mack, Nack, Ouack, Pack, and Quack are good examples of obedience(顺从) as they follow Mrs. Mallard through the city.

The Very Hungry Caterpillar(毛虫) and other books by Eric Carle

    The Eric Carle books have delightful pictures, full of bright colors and interesting detail. In The Very Hungry Caterpillar, children see the life cycle of a butterfly through the eyes of a caterpillar that is hungry. The children will laugh at all the food the caterpillar eats and be overjoyed by the beautiful butterfly at the end. All the Eric Carle books are fun for kids and parents, with simple ideas and beautiful art.

    There are many children's books available, and this list is only the beginning. However, these are all essential to a good children's library.

    There was a gardener who looked after his garden with great care. To water his flowers, he used two buckets(水桶).One was a shiny and new bucket. The other was a very old and dilapidated one, which had seen many years of service, but was now past its best.

    Every morning, the gardener would fill up the two buckets. Then he would carry them along the path, one on each side, to the flowerbeds. The new bucket was very proud of itself. It could carry a full bucket of water without a single drop spilled. The old bucket felt very ashamed(惭愧的)because of its holes: before it reached the flowerbeds, much water had leaked(渗漏)along the path.

    Sometimes the new bucket would say, "See how capable I am! How good it is that the gardener has me water the flowers every day! I don't know why he still uses you. What a waste of space you are!"

    And all that the old bucket could say was, "I know I am not very useful, but I can only do my best. I am happy that the gardener still finds a little bit of use in me, at least."

    One day, the gardener heard that kind of conversation. After watering the flowers as usual, he said, "You both have done your work very well. Now I am going to carry you back, and I want you to look carefully along the path."

    Then the two buckets did so. All along the path, they noticed, on the side where the new bucket was carried, there was just bare earth; on the other side where the old bucket was carried, there was a joyous row of wild flowers, leading all the way to the garden.