【推荐1】Scientists have long known that a crow （乌鸦）native to New Caledonia is able to use tools. The birds use them to remove food from deep holes. Now, American researchers have discovered a second species of crow with the same ability. They reported on their experiments with Alala crows, which are from the Hawaiian Islands.

In the experiment, the researchers placed pieces of food in holes inside the wood. The holes were too deep for the crows to reach with their beaks(鸟喙). But, by using small pieces of wood held in their beaks, Alala crows quickly got the food. They used small objects as tools, sometimes changing them by shortening too-long sticks. They also made tools from plant materials.

“The crows use their beaks as people use thumbs on their hands. Tool use is rare in the animal kingdom. ” said Chritian Rutz of University of St. Andrews. “Current evidence strongly suggests that tool use is part of the species’ natural behavioral pattern(行为模式). These birds had no special training in the study, yet most of them were skilled at handling stick tools. ”

Bird experts claim finding out that the crows use tools is important discovery. “It makes us rethink how to look at the whole tool-use idea now and encourages us to go out and look for things that we may have ignored before. ”

All the Alala crows left in the world live in Hawaii. There were less than 20 Alalas left in the late 1990s when scientists decided to bring them into a protected area. Now, it is reported that there are over 100 birds living there. Scientists plan to release a small number of the birds back into the wild later.

【推荐3】There are various ways in which to read body language so that you can understand how someone is feeling. Reading emotional clues （线索）is one of them.

Crying is considered to be caused by an explosion of emotion in most cultures. Often times crying is considered a sign of sadness, but crying can also be an expression of happiness. Crying can also come about through laughter and humor. Thus, when judging crying, you'll need to look for other signs to determine the meaning of the crying. Crying can also be forced in order to gain sympathy or to cheat others. This practice is known as " crocodile tears" , an expression that draws on the wrong idea that crocodiles" cry" when catching prey（猎物）.

Signs of threat include v-shaped eye brows, wide eyes, and an open or down-turned mouth. In a similar way, arm tightly crossed over the other is a common sign that the person is angry and is closing himself off to you.

When people show anxiety, they display increased facial movements, and their mouth made into a thin line. Individuals who are anxious may also play with their hands, unable keep them in one spot. Anxiety can also or have nervous legs. It can be conveyed when people seemingly unconsciously（无意识 地）tap their feet or have nervous legs.

Embarrassment can be expressed by turning the eyes or shifting them away. If someone looks down at the floor a lot, they are probably shy, afraid, or embarrassed. People also tend to look down when they are upset, or trying to hide something emotional. People are often thinking and feeling unpleasant emotions when they are in the process of staring at the ground.

There are also some signs of pride. People show pride by displaying a small smile, holding their head backward, and putting their hands on their hips.

【推荐2】Why is pink or purple a color for girls and blue or brown for boys?

The answer depends largely on cultural values as well as personal experiences. To the Egyptians, green is a color that represents the hope and joy of spring, while for Muslims, it means heaven. Red is a symbol of good luck in many cultures. In China, children are given money in a red envelope to bring good fortune in the New Year. For many nations, blue is a symbol of protection and religious beliefs. Greek people often wear a blue necklace hoping to protect themselves against evils.

People's choice of colors is also influenced by their bodies' reactions(反应)toward them. Green is said to be the most restful color. It has the ability to reduce pain and relax people both mentally and physically. People who work in green environment have been found to have fewer stomachaches.

Red can cause a person's blood pressure to rise and increase people’s appetites(食欲). Many decorators will include different shades of red in the restaurant. Similarly, many commercial websites will have a red“Buy Now” button because red is a color that easily catches a person's eye.

Blue is another calming color. Unlike red, blue can cause people to lose appetite. So if you want to eat less, some people suggest that eating from blue plates can help.

The next time you are deciding on what to wear or what color to decorate your room, think about the color carefully.

【推荐3】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.