Can you imagine astronauts' everyday life in space? They also need to eat,  sleep, exercise and relax. They do the same things as us, but they do them differently.

On Earth, we put food on a plate. Gravity holds the food down and keeps it on a place. But there is almost no gravity in space, so food can float （漂浮）away, and astronauts must eat carefully.

Sleeping is very different in space. Some astronauts like to float in the air, but most like to be in a sleeping bag. They tie the bag to a wall so that they won't float away at night.

Exercise is very important in space. On Earth,  your legs carry your body,  but in space, astronauts float, so they do not use their legs often. This is very bad for their legs, so they must exercise for thirty minutes every day.

After a day's work, astronauts relax. They may listen to music, read, watch films, play games, or talk to their friends and families on the radio. Sometimes they just enjoy floating in the air.

1.What does the underlined word "gravity" mean in Chinese?

2.Why do astronauts tie the sleeping bag to a wall?

3.What's the main idea of the passage?

Have you ever wondered?
1. Why do airplanes take longer to fly west than east?
It can take five hours to go west-east from New York (NY) to London but seven hours to travel east-west from London to NY. The reason for the difference is an atmospheric phenomenon known as the jet (喷射) stream. The jet stream is a very high altitude wind which always blows from the west to the east across the Atlantic. The planes moving at a constant air speed thus go faster in the west-east direction when they are moving with the wind than in the opposite direction.
2. What would happen if the gravity on Earth was suddenly turned off?
Supposing we could magically turn off gravity. Would buildings and other structures (建筑物) float away? What happened would depend on how strongly the things were attached to the Earth. The Earth is moving at quite a speed, moving at over a thousand miles per hour. If you turn something around your head on a string (细绳), it goes around in a circle until you let go of the string. Then it flies off in a straight line. ‘Switching off’ gravity would be like letting go of the string. Things not attached to the Earth would fly off in a straight line. People in buildings would suddenly shoot upwards at a great speed until they hit the ceiling. Most things outside would fly off into space.
【小题1】What information can we get from the first passage?

We have always been interested in the moon. 2000 years ago people already knew it moved around the earth and where it would be in the sky at different times of the year. At that time, everything about the moon was learned by watching it carefully in the sky.

When scientists could use telescopes(望远镜) to study the moon more closely, their ideas began to change. They could see the moon was made of rocks. Most scientists thought moon rocks would be different from those on Earth. This was because they believed the moon had once been a planet that had been caught in the earth’s gravity millions of years earlier.

In 1969 moon rocks were finally brought to the earth and studied. Much to their surprise, scientists found that, except for water, the moon and the earth were made of the same things. Once again new ideas were needed for this new information.

After years of study, most scientists now think that the moon was once part of Earth. They believe very early in its history, maybe 4 million years ago, something about the size of Mars hit Earth. This sent billions of rocks into space around our planet. These rocks slowly joined together and after many years became the moon.

In the future, even though our ideas about the moon may change again, we will still be interested in it.

1.From the passage we know the moon was made of_____________.

2.In the passage the writer wants to tell us ___________________.

3.Before 1969 most scientists thought the moon was ______________.

4.From this passage we can learn that ___________________.