It’s no secret that laughter works wonders for us. And much research has been carried out, which shows that laughter is good for our general health and well-beige. It has been found to release endorphins (释放安多芬), our bodies natural “feel-good” chemicals, into our blood. But as we grow older, we are more likely to find fewer things funny. A child will laugh on average 300 times a day. By the time we reach adulthood, his number is around 20. But what’s behind this? One theory suggests that it’s not a problem of losing our sense of humor but rather, as we take things a bit more seriously.

Laughter is very much something we do with others. Studies have shown that we are 30 times more likely to find something funny when we are with others than when we are by ourselves. But to laugh with others, we do need to feel a connection to them. We need to feel comfortable in their company. That’s why it can be difficult to laugh with strangers. Laughter is also very contagious and one person’s laugh can spread quickly through out a group of people. But often what makes us join in is the fear of standing out and being different. We laugh, even if we don’t really get the joke, especially in groups controlled by a powerful person.

When the head teacher tells a joke, for example, you laugh, even though later you might wonder if the joke was really that funny at all.

There are many different reasons why we laugh. Here are three widely accepted theories: The Incongruity Theory: It’s often the unexpected that makes us laugh. When things that we are familiar with suddenly take a turn into the unknown, our expectations are challenged and that often results in laughter. The Superiority Theory: We often find the mistakes and misfortunes of others funny. This would explain the popularity of online videos showing pranks (恶作剧). The Relief Theory: Laugh offers light relief. It explains why there are so many jokes about the darker things in life. By being able to laugh at them, we are able to face them more easily.

When we talk about an object, we might say it’s round, square, or soft. But when we describe the face of the earth, we use a word called landform (地貌). 【小题1】

There are many different kinds of landforms, including big mountains, soft hills and flat lands. A landform might be as large as a land or as small as a pool. Each landform has its own uniqueness (独特性).

The force of nature formed (形成) the landform.

This force could be wind, water, ice and so on. And it usually takes a very long time to form it. 【小题2】 For example, you may see many plains. It used to be a plateau or high hill, but as time passed, water and wind turned the plateau or high hill into a plain.

Another beautiful landform formed by water is a Delta. And there are hills and mountains. 【小题3】 Most mountains are like towers. They look very wonderful.

【小题4】 Understanding them is important to keep the homes where countless lives form.

When we look at animals, we know that they are not humans. But how do our closest friends dogs see us? Do they know that we are humans? Or do they actually think that we are just strange-looking dogs?

You may be surprised to know that many kinds of animals do not notice such differences very much at all. For example, the cuckoo (布谷鸟) lays its eggs in the nest of another bird. These birds will feed the baby cuckoos, even though they look nothing like their real babies. This is because the birds feed in an instinctive ways.

Other animals, it seems, will simply separate the world into animals they eat, and animals that eat them. When it comes to dogs, though, there is no simple answer to this question.

Sheepdogs leave their mothers when they are born. They grow up with sheep, and come to see them as their family. For this reason, they never attack the sheep, and help protect them, they probably think the sheep are dogs too, but we can’t be certain.

Similarly, if you keep a dog from birth, the way it sees the world will be different to a dog that grows up with other dogs. It will probably think it is the same kind of animal as you. This can even be true of humans. A Russian boy called Ivan Mishukov, born in 1998, was raised by dogs for two years and came to believe that he was a dog himself.