Put an ice cube from your fridge into a glass of water. You have a piece of string (线) 10 centimeters long. The problem is to take out that piece of ice with the help of the string. But you must not touch the ice with your fingers.

    You may ask your friends to try to do that when you are having dinner together. There is a saltcellar on the table. You must use salt when you carry out this experiment.

    First you put the string across the piece of ice. Then put some salt on the ice. Salt makes ice melt (融化). The ice round the string will begin to melt. But when it melts, it will lose heat. The cold ice cube will make the salt water freeze again.

    After a minute or two you may raise the piece of string and with it you will raise your piece of ice!

    This experiment can be very useful to you. If, for example, there is ice near the door of your house, you must use very much salt to melt all the ice. If you don't put enough salt, the water will freeze again.

    A traveller was staying in an Egyptian village. One day, she held up her camera to take pictures of the children. Suddenly the young ones began to shout at her. The traveller's face turned red and she apologized to the head for what she was doing, and told him she had forgotten that people in some places believed a person would lose his soul(灵魂) if his picture was taken. She explained to him the operation of a camera for a long time. Several times the head tried to say something, but he couldn't. When she believed that the head didn't fear any longer, the traveller then let him speak. With a smile, he said, "The children were trying to tell you that you forgot to take off the lens(镜头) cap!"

New research into a long-lived tree has shown some of the tricks that have helped it survive for thousands of years. The ginkgo(银杏树) is a huge, slow-growing tree with fan-shaped leaves, native to China, but planted in parks and gardens across the world. Some of the largest ginkgoes are said to be more than 3, 000 years old.

In order to discover how these and other trees can live for so long, scientists from the US and China studied 34 healthy ginkgoes of different ages. The team studied growth rings in each tree's trunk(树干), as well as cells(细胞) from the bark, leaves and seeds. They found that 600-year-old trees were just as healthy as 2-year-olds.

To learn more, the team then looked in detail at the DNA of nine trees aged between three and 667 years old. DNA is the chemical in the cells of plants and animals that holds instructions that tell any living thing how to grow and develop-including what to do at different times in its life At the beginning of a tree's life, DNA instructs the cells in a seedling to divide quickly so the tree grows rapidly. The cells also make special chemicals to help the young plant survive difficult situations, such as disease. As most trees grow older, their DNA tells their cells to divide more slowly (so growth slows down) and to make fewer chemical defenses(防御).

Ginkgoes, however, do things differently. The team found that although their growth finally slows, both young and old trees make protective chemicals." The secret is keeping a really healthy defense system," said researcher Richard Dixon." As ginkgoes age, they show no sign of weakening their ability to defend themselves from things like disease. "Other trees that live for a long time may have the same ability.

For all their defenses, though, ginkgoes cannot live forever--they finally meet with deadly accidents such as fire, disease and storms. While they last, however, these leafy trees are some of the most beautiful trees in the world.

The gentle giants of our oceans are whale sharks. It's the biggest whale shark and can reach as long as 41. 5 feet, and these amazing creatures are not only the biggest sharks, but they are also biggest fish of any kind.

Whale sharks have a lifespan of 70 years on average, and they spend their days gently swimming in the warm and tropical oceans.

Their teeth are the size of match heads, and while their jaws could be powerful, they have never tended to attack humans. Their teeth play no role in eating, as plankton (浮游生物) does not need to be chewed. They are to be found in numbers in the warmer oceans and they prefer the deep waters of open oceans. They tend to travel alone.

Several times a year they gather together in certain spots where plankton is plentiful. Those areas are all within a 30°north or south latitude from the equator. Sadly whale sharks are targeted by commercial fisheries at those spots.

How easy it must be for the fishermen to catch those beautiful creatures who can only swim at 3. 5 miles per hour! So great a loss in numbers have they suffered that whale sharks are now listed as one of the endangered species. Some countries have started to take measures to protect the whale sharks from extinction.

The Philippines, India and Taiwan have all banned the fishing, selling, importing and exporting of whale sharks for commercial purposes. However, the law doesn't seem to be effective because the hunting and killing still goes on today, especially in Taiwan and the Philippines. Each whale shark can fetch around $21,000. In parts of Asia they are known as the "money shark".

The mighty dollar wins again at great cost to our habitat, and we will not know what we have lost until we have lost it forever. Therefore, it is high time for us to do something for the whale sharks.

Are you a sports lover looking for skill development in the off­-season (淡季)?

Joy of the Game (JG) has been working for the past 10 years. Come and join JG to develop skills as you prepare for next season.

A new study reveals that pigeons (鸽子) can tackle some problems just like artificial intelligence, enabling them to solve difficult tasks that might challenge humans. Previous research has theorized that pigeons employ a problem-solving strategy, involving a trial-and- error approach, which is similar to the approach used in AI models but differs from humans' reliance on selective attention and rule use. To examine it, Brandon Turner, a psychology professor at the Ohio State University, and his colleagues conducted the new study. 

In the study, the pigeons were presented with various visual images, including lines of different widths and angles, and different types of rings. The pigeons had to peck (啄) a button on the right or left to indicate the category to which the image belonged. If they got it correct, they received food; if they were wrong, they received nothing. Results showed that, through trial and error, the pigeons improved their accuracy in categorization tasks, increasing their correct choices from about 55% to 95%. 

Researchers believed pigeons used associative learning, which is linking two phenomena with each other. For example, it is easy to understand the link. between "water" and "wet". "Associative learning is frequently assumed to be far too primitive to. explain complex visual categorization like what we saw the pigeons do," Turner said. But that's exactly what the researchers found. 

The researchers' AI model tackled the same tasks using just the two simple mechanisms that pigeons were assumed to use: associative learning and error correction. And, like the pigeons, the AI model learned to make the right predictions to significantly increase the number of correct answers. For humans, the challenge when given tasks like those given to pigeons is that they would try to come up with rules that could make the task easier. But in this case, there were no rules, which upsets humans. 

What's interesting, though, is that pigeons use this method of learning that is very similar to AI designed by humans, Turner said. "We celebrate how smart we are that we designed artificial intelligence: at the same time, we regard pigeons as not clever animals," he said.