The universe (宇宙) is everything out in space. Nobody _______ how large the universe is. When we talk about the universe, we _______ the Earth, the Sun, the Moon and all the stars, and the space between them.

Now let me tell you something about the _______. It is like a large ball. It _______ around the Sun. And _______ and land cover it. If you are in a spaceship and _______ the Earth from space, you will find that there are some large blue parts. They are the seas and about 70% of the Earth’s surface (表面) is water.

We live on the outside part of the Earth. Around us is the air. It takes the Earth 24 hours to turn in a full _______. When you see the Sun shining _______, it’s the day for you. But when the Earth turns you away from the Sun, everything around you becomes _______.

Can you tell me something else about the universe? I’m ________ in it and want to learn more about it.

The Americans were getting ready to send their first man to the moon. An old Irishman (爱尔兰人) was watching them on the television in the bar of a hotel. There was an Englishman in the bar, too, and he ______ the Irishman, “The ______ are very clever, aren't they? They are going ______ some men to the moon. It is a long ______ from the earth.”

“Oh, that's ______, ”the Irishman answered quickly. “The Irish are going to send some men to the sun in a few months. That's ______ away than the moon, you know.”

“Yes, it is,” the Englishman said, “______ it is too ______ for the people to go to.”

The Irishman laughed and said, “Well, the Irish aren't stupid, you know. We ______ go to the sun during the day, of course. We will go there ______. ”

The universe is really mystical(神秘的). Scientists have done lots of study about it but there is still much they haven’t discovered. ___ think that people have lived on the earth for many many years. However, we haven’t found life on any other planets _____.

There _____ eight planets going around the sun. The earth is one of them. There are humans, animals, plants and many other kinds of _____ on the earth. There is water and air, too. And compared to the other planets, the earth is not too _____ or too cold. None of seven other planets has a(n) _____ like that of the earth.

The sun and its planets are_____the solar system, and our solar system is a small part of a much larger group of stars and planets, called the Galaxy or the Milky Way. There are billions of_____ in the Galaxy, and our sun is only one of them.

Scientists have also_____many other galaxies in the universe. Their light has to travel for many years to reach us. So how______ is the universe? It is impossible to imagine______.

Scientists have sent spaceships to the planet Mars to take______photos. They have______ sent spaceships to travel outside the solar system. However, no spaceship has travelled far enough to reach other stars in _____ Galaxy.

When we see stars twinkling(闪耀) in the sky at night, we may think a lot:with so many stars in the universe, is there life out there in space? If there is life on other planets, what life will be like there? What transports do they use to travel______? Why don’t they visit us? We do not know the answers...