—Yes. She was busy with her exam, so she had no time to go to the party.

—         They often use them to play games instead.

A: What kind of book are you reading, Crystal?

B: It's about aliens.

A: Really? There's no such thing as aliens. You know that, right?

B: No, I don't know. I mean, I don't those stories about aliens on Earth, but there could be  on other planets. There must be  of other planets in the universe.

A: But those planets may be very far away.

B: Well, one day we will be able to  a very fast spaceship, and we will be able to go there. Or perhaps the aliens can travel huge distance very .

A: Maybe. Can I look at the book when you've finished?

    We want to explore and try to better understand the world in which we live; Space exploration is one of the ways. Through the exploration of space, we can begin to unravel the mysteries of our universe, and to better know our living environment.

    Space exploration provides us with knowledge about the beginning of our solar system, our own planet and ourselves. It also helps answer the questions that have puzzled us for many years. Solar system exploration is important because it is good for us.

    Space technology has become an important part of our daily lives. Some technology uses satellites to communicate. Satellites are also used to examine the changes in the Earth's climate and seas, for weather report and for military. We also use satellites in food production. Because of the use of space technology in crops, fewer and fewer people will suffer hunger.

    The space program provides a chance for nations to work together. The cooperation(合作) promotes peace and understanding between governments and their people. Many governments have taken part in the space technology, including the United States, Russia, Japan, the European nations and India. In the near future, other nations will take part in it. In fact, the United States remains the leader in new space technology.