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.

    It is easier to float in the ocean than it is to float in a swimming pool.Do you know why?

    Ocean water is full of salt--and salt water can hold up more weight than fresh water.See for yourself!

You will Need:

3 cups of warm water

Measuring cup(量杯)

Wide-mouthed jar

Salt

Spoon

Raw(生的)potato

You Will Do:

⒈Pour 1.5cups of warm water into the jar.

⒉Add 1/3 cup of salt.

⒊Stir(搅拌) until the salt is completely dissolved.

⒋Add another 1.5 cups of water.Pour it slowly over the back of the spoon into the jar so that the two liquids will not mix together.

⒌Gently place the potato into the jar.Do not drop it.

    What Will Happen:

    The potato will sink--but only halfway!

    Why?

    Salt water is heavier than fresh water,so it will stay on the bottom.The fresh water will remain on top.

    The potato is heavier than the fresh water,but it is lighter than the salt water.That is why the potato will sink halfway down.

    Astronomy (天文学) is the oldest science known to man. Thousands of years ago man looked at the stars and wondered about heavens(天堂). But the six planets that he could see with his eyes alone limited man.

    The Greeks studied astronomy over 2,000 years ago. They could see the size, color, and brightness of a star. They could see its place in the sky. They watched the stars move as the seasons changed. But the Greeks had no tools to help themselves study the heavens.

    Each new tool added to the field of astronomy helped man reach out into space. Until there were telescopes(望远镜), man did not know much about the moon. He did not know that the planet called Saturn(土星) had rings around it. His sight was so limited that he could not see all the planets. In the early 1700s, people thought there were only six planets. Pluto (冥王星), the last of the nine planets to be discovered was seen until 1930.

    Before the spectroscopes (分光镜), man didn't know what kind of gas was in the sun or other stars, without radio telescopes(射电望远镜), we did not know that radio noise came from far in space.

    Today, astronomy is a growing science. We have learned more in the past fifty years than in the whole history of astronomy.

    There is a breakthrough in building aircrafts. Bendable wings covered with overlapping(部分重叠) pieces resembling fish sizes could be used to build swifter, fuel-efficient aircraft, a new study finds.

    Nowadays, conventional aircrafts typically rely on ailerons (副翼) to help control the way the planes tip as they fly. However, when the Wright brothers flew the first airplane, Flyer 1, over a century ago, they used no ailerons but wires and pulleys that twisted the wood-and-canvas wings, to control the plane.

    Scientists have long sought to develop aircrafts that can alter their wings during flight, just as birds can. However, most previous attempts have failed because they relied on heavy mechanical control structures within the wings. These structures were also complex and unreliable, said Neil Gershenfeld, a physicist and director of the Center for Bits and Atoms at Massachusetts Institute of Technology (MIT).

    The new wing consists of a system of tiny, strong, lightweight modules. The shape of the wing can be changed uniformly along its length using two small motors, which apply a twisting pressure to each wingtip. These wings are covered in “skins” of overlapping strips of flexible material resembling fish sizes. These strips move across each other as the wings alter, providing a smooth outer surface, the researchers explained.

    Wind-tunnel tests of these wings showed that they at least matched the aerodynamic properties of conventional wings, at about one-tenth the weight. Initial tests using remotely piloted aircrafts made with these wings have shown great promise, said Benjamin Jenett, a graduate student at the Center for Bits and Atoms at MIT.

    The new modular structures the scientists developed could be manufactured quickly in mass quantities and then installed by teams of small robots. These modular structures also can be disassembled more easily, making repairs simpler.

    “Still, the first aircraft built using this strategy will not be a passenger jet, ”Gershenfeld said. “Instead, the technology will likely first be tested on unmanned aircraft, leading to drones (无人机) that can fly for a long time, to help deliver internet access or medicine to remote villages and do some rescue works.”

    Summer is approaching and the following books can accompany you during the hot season.

◆And Then Comes Summer by Tom Brenner

    The smell of fresh-cut grass. The coldness of ice cream on your tongue. The sound of crickets(蟋蟀) at night, This romantic feast for senses is as much a celebration of the season as it is a summer bucket list! Attractive illustrations(插图)and descriptive text warm your heart and inspired play like never before.

Available from Amazon. $11.28

◆Three Little Words by Amy Novesky

    Dery's “Just keep swimming!” message of perseverance is perfect for any one who has ever felt like they were drowning. Follow Dory an unforgettable adventure as she finds her way in this beautiful watercolor adventure of friendship and survival.

Available from Amazon. $12 06

◆There Might be Lobsters by Carolyn Crimi

    Meet Suki. She's a small dog with a big fear of the beach. When a rescue is in order, Suki saves that the day, proving that there's nothing to fear but fear itself. Quite possibly the perfect picture book for anxious kids fearful to try new experiences, this timeless treasure opens the door to calming dialogues and messages of bravery and victory.

Available from Amazon. $11.84

◆Jabari Jumps by Gaia Cornwall

    You know that feeling when you're as excited as you are scared to make a leap? That's how Jabari feels about his first jump off the diving board. He knows how to swim. He knows jumping off sure looks fun. But does he have what it takes to take a try? With some gentle encouragement from his loving father, Jabari jumps.

Available from Amazon. $11.26

    As computers become all the more popular in China, Chinese people are increasingly relying on computer keyboards to input Chinese characters. But if they use the computer too much, they may end up forgetting the exact strokes （笔画）of each Chinese character when writing on paper. Experts suggest people, especially students, write by hand more.

    Do you write by hand more or type more? In Beijing, students start using a computer as early as primary school. And computer dependence is more wide-spread among university students. Almost all their writings are typed on a computer.

    All the students interviewed say they usually use a computer.

    It's faster and easier to correct if using a computer. And that's why computers are being used more and more often to modern education. But when people are taking stock in computers increasingly, problems appear. "When I'm writing with a pen, I find I often can't remember how to write a character, though I feel I'm familiar with it."

    "I'm not in the mood to write when faced with a pen and paper."

    Many students don't feel this is something to worry about. Now that it's more convenient and efficient to write on a computer, why bother to handwrite?

    Many educators think differently. Shi Liwei, the headmaster of a famous primary school in the capital said "Chinese characters enjoy both practical and aesthetic(审美的) value. But those characters typed with computer keyboards only maintain their practical value. All the artistic beauty of the characters is lost. And handwriting contains the writer's emotion. Through one's handwriting, people can get to know one's thinking and personality.

    Beautiful writing will give people a better first impression of them."

    To encourage students to handwrite more, many primary schools in Beijing have made writing classes compulsory(必修的)and in universities, some professors are asking students to turn in their homework and essays written by hand.