How are you? This week we did a project on the history of London.

My grandfather said that London in the 1950s was a terrible place to live because the air pollution was so bad. There were many factories and they caused a lot of smoke. The smoke caused heavy black fog in the sky. The people of London called this “smog”.

Sometimes the smog was so thick that people could not see anything at all. Taxis and buses could not go anywhere as it was too dangerous to drive. The smog was also harmful to people’s health, and some people found that it was difficult to breathe.

In 1965, the government made new laws about the pollution, and the air got much cleaner. Today it is clean and we never see smog in London, and now people find that it is not difficult to breathe any more.

Since the 1950s, people from all over the world have come to live in London. My grandfather says that this is one of the best changes. Now he can eat food from India, China, Italy and Germany in his neighbourhood.

I like living in London today, and I am happy to have friends from all over the world.

Write back soon.

Most of us use alarm clocks to wake up at the right time for school or work. We look at our watches to know the right time for the bus or train. However, there is also a right time to eat, sleep, exercise, and take medicine. We can’t look at a clock for the right time for these activities. We must listen to the clock inside our bodies：the biological(生物的) clock.

Barbara Wells exercised every morning. She woke up at 6：00 a. m. She ran about two miles before she went to work. But Barbara’s 1egs and back started to hurt. She did some exercise before she ran. But her legs and back still hurt. She ran slower, but the pain didn’t stop. Barbara talked to her doctor. The doctor said, “Don’t run in the morning. Try to exercise later in the day. That is the time when your body is at the right temperature for exercise after work after. "Her legs and back didn’t hurt anymore.

Today, doctors are learning more about chronobiology(生物钟学),the study of biological clocks. They are learning about the importance of time for our bodies. For example, it is best for people to go to sleep on time every night and to eat only when they’re hungry. Also, doctors discovered that some illnesses, such as heart attacks, occur(发生) most often in the morning. This information tells them that the best time to take heart medication(药物) may be   at night. When patients take heart medication at night, they may prevent a heart attack in the morning.

Many doctors believe chronobiology can help us live healthier lives. It may be the right time to listen to these doctors !

We need to know how much of what food to eat to be healthy. Here is a picture about food groups and why they are good for our health.

It is important to understand how food is used. When we eat food, our bodies use the food to make energy. If we are eating the correct food and the correct amount of the food, we will have enough energy for our bodies and minds to work properly. It is necessary to read the labels（标签）on the foods in a shop as well. The labels tell us what the food has in it. They give us information about how healthy the food is.

There are many people who do not eat enough right food. This could be because they are too poor to buy the right food. These people may have what we call malnutrition（营养不良）. Children that have malnutrition do not grow properly and they cannot concentrate（集中精力）at school.

If things are very bad, they can become sick and even die. Malnutrition is a great problem in some poor parts of Asia and Africa.

It is also important to drink lots of water. Our bodies are made up of about 76% water. We need to drink six to eight glasses of water a day. Water keeps our skin healthy. It also makes sure that our bodies work properly. If we do not drink enough water, we can get headaches, stomachaches and our kidneys（肾脏）will not work normally.

If we want to have minds and bodies that work properly, we need to make sure that we eat correctly.