Imagine the situation. You are driving along a desert or on a mountain. You have no idea where you are. You passed the last house two hours ago. Then your car breaks down. It is night and it is cold. You have no mobile phone. What do you do? Well, next time take a GPS with you. This invention may be able to help you. It is a device(装置) which uses satellites to find the user’s position. It can find your position to within 20 metres. A GPS cannot start your car, but at least you will know where you are.

   GPS, which means Global Positioning System, is a small radio receiver. It looks like a mobile phone. You can hold it in your hand, or put in your pocket. It is sometimes put into a watch or a telephone. We also find GPS devices in cars, planes, or boats. Some of these devices have electronic maps, so you know where you are. For example, in a city they can tell you the name of the street .

There are three parts to the Global Positioning System. The first part is the receiver. You can hold it in your hand, or have it fixed into your car, plane, etc. The second part is a group of satellites orbiting the Earth. The receiver contacts at least four of the satellites and calculates(计算) its position. The third part of the system is a network of ground stations. They are all over the world. They control the satellites and make sure they are working well.

   Some people think that in the future the GPS will be as common as the mobile. They are becoming cheaper and more and more accurate(精确的). There are also new uses for the GPS. Perhaps they will become like watches. Everyone will have one and you will never be lost again.

Have you ever seen people building houses? To build a house, you need workers. They use their hands, tools (工具) and machines to put things together. In fact, building the ISS(国际太空站) is the same. The difference is that the workers are astronauts. They walk in space and use robots' arms and hands to do their work.

   In the space station, astronauts always feel easy, because the temperature there is always about 21℃. But outside the station, it can be too hot or cold for people, In the sunlight, it's about 120℃; in the shadow of the station, it's about -85℃. So when astronauts walk in space, they have to wear heavy clothes — spacesuits. These special clothes can make the astronauts feel as comfortable as in the space station.

  Spacesuits also keep astronauts safe from flying rubbish (垃圾) in space. Each time people go into space, they leave rubbish there. So astronauts should be careful because there's a lot of rubbish—some rubbish goes many times as fast as a plane!

   Space walking is not easy, and it can be dangerous. So getting ready for it takes a lot of time to learn. Astronauts will need to do 160 space walks to finish their work in the ISS. That will take about 1,900 man-hour of work.

You love reading, but you've read all your books four times, and are tired of reading the same ones. You're planning to go to the library, but don't know what kind of books to get. With the right knowledge, it's easy to choose a good book!

Answer these questions first. What authors do you like? Research books by the authors you've enjoyed, and you can get more of the same type of books. What are your interests? Type your hobbies into your library catalog search. By doing this, you will find books that you might like. Is there a type of book you would like to try? If there is, search the book and read the summary. This will help you decide if the book is right for you.

Search your house next.Often good books are quietly collecting dust in your own house.Maybe you forget about one, or someone who is living with you has a couple of good books. Also by searching your house, you can find some books that you can read, and they won't even cost you any money.

Then, ask someone to recommend a good book. You can ask your older brother or sister, your mom, your dad, your best friend, or even your English teacher. Local bookstores oft en have wonderful recommendations. And when they get to know you, it's even better! You should ask people who like the same type of books, so that you can get books that match your need.

 Join a book club, please. Being a book club member is often a way to experience new books with other members. Joining a book club or setting up a book club helps you know who else likes the same books as you, and you can read books that others have read and discuss them.

Finally, read the first part of each book. Of course, if you have many books, this can betime-consuming. Reading the first part of a book can help you know what books and types of books that you like, and you won't have a hard time looking for books again. CBD

Many parents today worry about their children's diets. Then what is a healthy diet for children? Miss Jones from Happy Children Hospital gives the following advice:

   Children shouldn't eat food with too much salt, because it can cause high blood pressure(高血压)

   Children should eat food with less fat, oil and sugar. They should not eat too much junk food.

   Fruit and vegetables are rich in vitamins(维生素). Children need to eat fruit and vegetables often.

   Water is important to everyone. Children need to drink enough water every day.

   Children need to eat breakfast every day. It is good for their bodies and minds.

Many parents today worry about their childrenˈs diets. Then what is a healthy diet for children? Miss Jones from Happy Children Hospital gives the following advice:

◆Children shouldnˈt eat food with too much salt, because it can cause high blood pressure(高血压).

◆Children should eat food with less fat, oil and sugar. They should not eat too much junk food.

◆Fruit and vegetables are rich in vitamins. Children need to eat fruit and vegetables often.

◆Water is important to everyone. Children need to drink enough water every day.

◆Children need to eat breakfast every day. It is good for their bodies and minds.

Everyone knows that exercise is important. We need to exercise. Doctors say it is good for us. It keep our bodies strong. When the daytime comes, we must get up. This is the time for exercise. Exercise means doing things with the body. There are many ways to exercise. You can walk, run, swim, skate, or play ball games. Make sure you excise in the following ways: you have to like what you’re doing. Exercise enough---but not too much. It is good to exercise twice each week. Thirty minutes each time is enough. Try all kinds of things until you find one, two or three sports that feel right for you.

Exercise can be fun. Friends can exercise together at fitness center, or they can play sports together. How do you exercise? 

If you go to a fast food restaurant, you will probably see a lot of teenagers (青少年).Today, many teenagers are overweight because of their bad eating habits. Most teenagers love food with a lot of fat(脂肪), oil, salt, and sugar. People often call this kind of food" junk food".  But bad eating habits go beyond(远不止) fast food. We find many teenagers eat unhealthily. Some donˈt have breakfast before they go to school. During the day, some donˈt have a nice meal for lunch. In a survey at one school, scientists found that more than two-thirds(三分之二) of the students didnˈt follow a healthy diet (饮食). They didnˈt like vegetables, and many of them didnˈt like to eat fruits. They liked to eat food with a lot of salt, sugar, or fat. Parents today also worry about their childrenˈs diet. Some doctors give the following advice:

★Teenagers shouldnˈt eat too much junk food. 

★Teenagers shouldnˈt eat food with too much salt.  

★Teenagers should eat food with less fat, oil and sugar.  

★Teenagers need to eat some fruits and vegetables every day. Fruits and vegetables are rich in vitamins(维生素) and have little fat. 

★Teenagers need to eat breakfast every day. This is good for their body and mind. 

★Teenagers need to drink more milk. Milk will help them grow.

Australia is the greatest island in the world. It is to the south of the equator. So when it is summer in our country, it is cold winter in Australia.

    Australia is big, but the population（人口）there is small. The population is the same as that of Shanghai, a city of China. Australia is young and diverse nation and Australian people come from many different countries.

    Australia has many, many sheep. After a short drive from town, you will see sheep around you. You can also find kangaroo has a “bag” below its chest. The mother kangaroo keeps its baby in the “bag”.

    Australia is considered to be a relaxed, informal society（社会）. When greeting others, students and young people say “Hello” or “Hi”. Sometimes they will say “How’s it going?” or “G day”. In more formal（正式的）situations they usually shake hands the first time they meet. “Good morning”, “Good afternoon” or “Pleased to meet you” are formal greetings. English is Australia’s national language.

  Summer is very hot and kids need to drink enough water. However, many kids don’t, according to a new study published in the American Journal of Public Health.

The study’s lead author, Erica Kenny, a scientist at Harvard’s T.H. Chan School of Public Health, found that many kids were simply not drinking enough water.

Kenney and her team examined data from a group of 4,000 children, aged from 6 to 19. While looking through the survey results, she noticed that more than half of the kids who took part in the study were dehydrated. Of that group, boys were 76% more likely than girls not to have enough water in their systems.

 How much is enough?

70% of the human body is made up of water. Not drinking enough water can lead to health problems such as headaches, poor physical performance (体质), and even more serious problems. Your body needs more water when you are in hot climates, when you are physically active or when you have a fever.

The United States National Agriculture Library says kids need between 10 and 14 cups of water every day. The water can come from a mix of drinks or foods that have high amounts of water, such as melons or tomatoes. Tips for making sure you drink enough water.

 ◆Carry a water bottle with you.

 ◆Freeze some water bottles. Take one with you for ice-cold water all day long.

 ◆Choose water instead of juice when eating out.This tipcanalso help with weight management.

 ◆Add a slice of lemon to your water. This may improve the taste, and you might just drink more water than you usually do.

Everyone knows that exercise is important. We all need to exercise. Doctors say it is good for us. It makes your heart and body strong. Children who often exercise are more alert(灵活).

There are many ways to exercise. You can walk, run, swim, skate, or play ball games. Make sure you exercise in the following ways: you have to like what you’re doing. Exercise enough but not too much. It’s best to exercise twice each week. Thirty minutes each time is enough. Try all kinds of things until you find one, two or even three sports that feel right for you.

You can exercise at fitness centers. They have a lot of equipment there. The equipment will help exercise your arms, legs and other parts of your body to make you fit. Some people buy equipment for their homes. But it is very expensive.

Exercising can be fun. Friends can exercise together at a fitness center, or they can play sports together. How do you exercise?