A wealthy man loved his son very much. As he wanted his son to lead a happy life, he decided to send him to see a wise old man for his advice on happiness.

Jackie is writing a summary（总结）and feedback about School Day to his teacher.   

There's much to see under the sea, but you need to remember that light behaves differently in water than in air. The objects appear closer to you than they exactly are. You might find yourself reaching out to touch something and completely missing it.

Objects underwater will appear larger than they would on the surface, too. Be careful not to tell any stories about the big fish that got away. That fish might not be so big after all! It's just because sometimes things can seem to be as much as about 33 percent bigger in water!

What's more, in deeper water, colors just don't seem as bright. In fact, it looks as if some colors are missing. Remember the color of an object results from the wavelengths (波长) of light that are reflected(反射) from its surface. And light is taken in as it moves down through the water.

Swimmers wear wet suits to keep warm underwater. Let's take a bright red, yellow, and blue wet suit as an example. These colors are hard to miss on the surface of water. Watch carefully the changes in color as you descend in the water. The red part now looks almost black because the red light wavelengths, the longest among these three colors, are missing. As you go down deeper, the same thing will happen to the yellow part and in the end to the blue part. Even at a place of about 6 to 9 meters underwater, you will look terrible, like a ghost(鬼怪)! And you have to wait for your return to the surface to enjoy the bright colors again.

The world is divided into two important parts. One half of the world is rich and the other half is poor. In the poor part, a lot of people never get enough to eat. In the rich part, a lot of people eat too much. In one part, children are hungry and in the other, a lot of people are fatter and fatter and have to go on diets or do some exercise to lose weight. For example, a dog or a cat in North America eats better than a child in the poorer countries.

The poor countries have some difficult problems. Sometimes the land is too poor to grow anything on. The land can get better, but people have to do a lot of things first. More experts should go there to teach people how to enrich their land and how to find water.

But rich countries have problems too. They are not always pleasant places to live in. Sometimes the air is too dirty to breathe and the rivers are too dirty to swim in or to take water. The roads and the streets are full of people and buses. Cars usually move very slowly. Noise is terrible. A lot of people do not have houses to live in. People must do something about these problems. We should do something to make the air and the rivers clean and build more houses. But it will take a long time.

Different lives in the world