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 (癌症). 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.

    Flying on a plane for the first time can be frightening. It can be extra 1 for children who have autism (自闭症). When Linda Diaz was 2 a vacation to Disney World four years ago, she wanted to make flying a 3 experience for her son, Andy, who has autism.

    She called Minneapolis-St Paul International Airport (MSP) to see what could be done. 4, the airport didn't have programs to help Andy. So Diaz 5 the family's flights and 6 drove 1, 500 miles to Orlando, Florida.

    Soon after that drive to Disney World, a program started at MSP. It is to help make flying 7 for kids like Andy. The program is called Navigating MSP. It holds 8 every month for anyone who has 9 about flying. The program is not 10 for people with autism. Airline workers help 11 get used to the airport and planes. It helps them to be less frightened of flying. When they 12 fly, they are not as worried.

    When Andy was 13 years old, his first 13 ride was planned. He went through a practice with his family. George Callow, an officer at the airport, helped the family through the safety checks. Callow said the visiting families got on a plane, 14 it was not going anywhere. It was just for them to 15.

    After the last family arrived, the pilot greeted the families over the speaker, "Welcome aboard our flight to 16." After greeting the pilot and flight attendants, passengers went to their 17. But Andy had other plans. Frightened by his new surroundings, he ran down the aisle (走廊) of the plane, 18 a way out. Volunteers suggested that Andy might be most 19 in the front row. They were 20. Once seated, Andy was quiet and kissed his mother on the face. He felt better about flying now.

    Sometimes people add to what they say even when they don't talk. Gestures are the "silent language" of every culture. We point a finger or move another part of the body to show what we want to say. It is important to know the body language of every country or we may be misunderstood.

    In the USA, people greet each other with a handshake in a formal introduction. The handshake must be firm. If the handshake is weak, it is a sign of weakness or unfriendliness. Friends may place a hand on the other's arm or shoulder. Some people, usually women, greet a friend with a hug.

    Space is important to Americans. When two people talk to each other, they usually stand about two and a half feet away and at an angle (角度), so they are not facing each other directly. Americans get uncomfortable when a person stands too close. They will move back to have their space. If Americans touch another person by accident, they say, "Pardon me" or "Excuse me". Americans like to look at the other person in the eyes when they are talking. If you don't do so, it means you are bored, hiding something, or are not interested. But when you stare at someone, it is not polite.

    For Americans, thumbs-up means yes, very good, or well done. Thumbs-down means the opposite. To call a waiter, raise one hand to head level or above. To show you want the check, make a movement with your hands as if you are signing a piece of paper. It is all right to point at things but not at people with the hand and index finger (食指). Americans shake their index finger at children when they scold them and pat them on the head when they admire them.

    Learning a culture's body language is sometimes confusing. If you don't know what to do, the safest thing to do is to smile.