There are many kinds of food in the world. Scientists learn a lot about them. They say that there are some kinds of food people must eat every day. For example, people must eat some green and yellow vegetables. We shouldn't eat too much meat. People also need to eat some fruits, bread and rice. Of course our bodies need some water and milk.

    Scientists say people in different countries and different places eat different kinds of food. They cook food in different ways. Different people eat at different times. In one place, people eat once or twice a day. But in another place, people eat three or four times. The scientists say when to eat and how many times to eat are not important. What we eat is the most important thing.

    Nowadays(现在), the world faces two problems. People in some places, for example, in Africa, are not full. Many people are eating junk food. It's bad for people's health. So it's our duty to make everyone full and make everyone healthy.