To prevent the deserts coming near, China has planted billions of trees—to replace destroyed forests and as barriers against the sand. This isn't a cure, though, say experts, as thirsty trees can make the problem worse by taking in groundwater.

    “Planting tress is one way, but it isn't that simple. It doesn't solve the basic issue of water resources,” says Wu Bo, a professor. “We need to calculate how much water the trees will absorb, or else it could have a negative effect.”

    Villagers in Zhengxin have taken on this challenge, with limited success. When the irrigation channels began to run dry, Lu Xianglin switched from wheat to cotton on his land. He also planted trees to protect his fields from sandstorms. He says he still gets good yields（产量） using flood irrigation and earns a good income for his family.

    Other farmers haven't stuck it out（坚持到底）: about one in three have left Zhengxin in the past 10 years after their wheat crops died. Young people who can find jobs in the towns rarely return.

    Last week, Mr Lu joined the other men in his village on a government-arranged trip to see the land that has been set aside for their relocation, nearly 40 miles to the south. The next day, he was back, shaking his head at the plan. The idea of uprooting his family troubles him, as does the idea of giving up the land that fed his forefathers. He prefers to stay and keep up the fight.

    “With enough water, this problem can be solved,” Lu says. “We can plant trees and grass, and they will grow bigger. That will stop the desert.”

    Experts say that farmers could switch to drip irrigation （滴灌）to lessen their water intake for growing crops. Elsewhere in the region, farmers have built brick greenhouses as part of a plan to grow vegetables using less water. Roadside signs urge farmers to “Save Water, Protect the Environment”.

    People around the world are superstitious about numbers; even those ancient Greeks believed that all numbers and their multiples had some mystical significance.

    Those numbers between 1 and 13 were in particular to have a powerful influence over the affairs of men.

    For example, it is commonly said that luck, good or bad, comes in threes; if an accident happens, two more of the same kind may be expected soon afterwards. The arrival of a letter will be followed by two others within a certain period.

    Another belief involving the number three has it that it is unlucky to light three cigarettes from the one match. If this happens, the bad luck that goes with the deed falls upon the person whose cigarette was the last to be lit. The ill-men linked to the lighting of three things from one match or candle goes back to at least the 17th century and probably earlier. It was believed that three candles alight at the same time would be sure to bring bad luck; one, two, or four, were permissible, but never just three.

    Seven was another significant number, usually regarded as a bringer of good luck. The ancient astrologers believed that the universe was governed by seven planets; students of Shakespeare will recall that the life of man was divided into seven ages. Seven horseshoes nailed to a house will protect it from all evil.

    Nine is usually thought of as a lucky number because it is the product of three times three. It was much used by the Anglo Saxons in their charms for healing.

    Another belief was that great changes occurred every 7th and 9th of a man's life. Consequently, the age of 63 (the product of nine and seven) was thought to be a very perilous time for him. If he survived his 63rd year he might hope to live to a ripe old age.

    Thirteen, as we well know, is regarded with great awe and fear. The common belief is that this derives from the fact that there were 13 people at Christ's Last Supper. This being the eve of his betrayal, it is not difficult to understand the significance given to the number by the early Christians.

    In more modern times 13 is an especially unlucky number of a dinner party, for example. Hotels will avoid numbering a floor the 13th; the progression is from 12 to 14, and no room is given the number 13. Many home owners will use 12 1/2 instead of 13 as their house number.

    Yet oddly enough, to be born on the 13th of the month is not regarded with any fear at all, which just shows how irrational we are in our superstitious beliefs.

    Often in Scotland it can feel like the only difference between summer and the rest of the year is that it doesn't snow. (This isn't a guarantee!) But when the weather is good, it's a truly special place-here are some things you can do in summer when the weather is nice.

    See

    With the richest wildlife across the UK, take the chance to see some of the less common sites. On the West coast of Scotland there are lots of places where you can take a boat trip to see many kinds of whales. If you prefer dolphins, you can see the most northerly colony of bottlenose dolphins (海豚) in the world just off Inverness in the Moray Firth. Of course it's likely that you'll see seals (海豹) and many other animals on these trips too.

    Do

    The waves of Thurso right in the north of Scotland are just great. If you're not feeling brave enough to go in the water and prefer to watch from the safety of the shore then there're several major surf contests held there.

    Another very Scottish activity ideal for good weather is “Munro Bagging”. Named after Sir Hugh Munro, the 218 mountains in Scotland over 914m high are called Munros and walkers try to see how many they can climb in a set amount of time. This is not easy though-conditions can change suddenly and many of the routes are very tough (艰难的).

    Eat

    Thanks to a large Scottish-Italian population, there are too many specialist ice cream sellers. One of the most famous of them is Nardini in Largs, Ayrshire. Not only can you watch people actually make ice cream but you can sit and eat in a beautiful refurbished (翻新的) 1930s building facing the river Clyde. There's even a piano player at the weekends.

    Maui, one of the most beautiful islands in the world, is a dream place for a visit and there are so many attractions for you.

    HALEAKALA

    Mt. Haleakala is 10,023 feet high and is one of the two volcanoes that created this incredible Hawaiian island. Haleakala National Park offers a variety of activities, making it one of the most revisited attractions in all the Hawaiian Islands. The most popular activities include enjoying sunrise and sunset, hiking, and backcountry camping on Maui.

    ROAD TO HANA

    There are many ways to experience the Road to Hana, and the sleepy coastal Town of Hana, Maui. Visitors can go by group and private tours, or explore on their own by renting a vehicle. Beginning at the historic Town of Paia, visitors can enjoy decorated coastlines all the way to Hana, world-famous beaches in Hawaii, tropical landscapes, waterfal.ls, scenic lookout points, and cultural attractions that mark significant points in Maui's unique Hawaiian history.

    HO'OKIPA BEACH PARK

    Ho'okipa Beach Park is one of the most famous beaches in the world for professional surfing and windsurfing. In the ancient Hawaiian language, “ho'okipa” means hospitality, which is exactly what this Beach Park offers! At Ho'okipa, visitors can see the powerful coastline from the top parking lot for amazing photo opportunities. Or you can go to the sand for afternoon BBQ's and the glorious Maui sunshine.

    OHE'O GULCH POOLS

    The Ohe'o Gulch Pools, more commonly referred to as the Seven Sacred Pools, is a wonderful place to explore Maui on vacation. The lower pools are more easily accessed, and perhaps the best choice for visitors who want to jump in. Due to the popularity of the Seven Sacred Pools, it is highly suggested to arrive early for a chance to enjoy privacy in this beautiful location.

    There are several ways you can find out about the countries and places you wish to visit. You can talk to friends who have traveled to the places, you can go and see a colour film about them, or you can read a travel book.

    It seems that there are three kinds of travel books. The first are those that give a person al, subjective(主观的) idea of travels which their writer has got himself. These books can be useful if the writers share their traveling experiences with others. The second kind are those books which give objective(客观的) information of things to be done and seen. If a cultured person has written such a book about the facts of a place, then it is more useful. The third kind are those books which are called “a guide” to some place or other. If they are good, they will describe and explain the place in detail. Like the first kind, they can be interesting and exciting, but their main purpose is to help the reader plan his travel in the most practical way. Whatever kind of travel book you choose, you must make sure that the book does not describe everything as interesting, exciting or fantastic. You must also keep an open eyes on its date of publication(出版) because travel is very practical matter and many things change quickly in the 21st century. Finally, you should make sure that it's easy to find the useful information for you travel.

I was asked by a reader recently why so many animals seem to have pink ears，when their bodies are all different colours? The truth is that most animals actually don't have pink ears. Let us explain.

Near the equator (赤道), where the climate is hot, animals are likely to have darker skin, including on their ears. Think of the African elephant, which has quite dark ears. In colder climates, skin colour is usually lighter and often pink.

Why is skin colour different in different climates? Skin pigmentation, which is what gives skin its colour, can protect against sunburn and skin cancer. When animals live in colder parts of the world, they don't need it as much to survive. Light-coloured skin also helps animals stay warmer because it reduces heat loss, which is useful if you're in a colder climate.

For most animals, the colour of their fur or other body covering has generally developed as camouflage. That allows animals to mix into the background and avoid being eaten, or for predators (捕食者) to remain hidden during hunting. One example is the sandy-coloured coat of the desert fennec fox, which uses camouflage for both hunting and hiding.

By the way, in many animals, ears come in many different shapes and sizes. For example, in bats, the serval (a type of African wildcat) and the fennec fox, the ears are large compared to their body size—this helps them hear better because it allows them to sense more sound waves. Naked mole-rats have tiny ears because they need to dig a lot. Big ears would get in the way. The other downside of big ears is that you can lose a lot of body heat. That's why animals that live in really cold places, like the Arctic fox, have quite small ears.