1 . If someone asks you, “What colour is the sky?” I think you will answer “blue”. I’m afraid that you are wrong. The sky has no colour. It looks blue because we are looking at the blue sunlight. It is shining on little bits of dust (灰尘) in the air.

Is the sky full of air? I’m sure that you have asked this question, too. We know there is air all around the world. But we couldn’t fly very high because as we go high, the air gets thinner (更稀薄的). If we go far enough (足够的) away from the earth, we find there is no air.

Maybe we can answer some questions now. What is the sky? Where is it? The sky is space. It’s all round the world. In space there is nothing, but only the Sun, the Moon, the Earth and all the stars.

2 . Many people believe that, by the year 2100, we will live on the planet Mars. Here is what life could be like.

First of all, transport should be much better. By 2100, spaceship can travel at half of the speed of light.     1    

Secondly, humans need food, water and air to live. Scientists should be able to find plants that can grow on Mars. These plants will provide us with food and air.

    2     We could easily jump too high and fly slowly away into space. To prevent this, humans on Mars have to wear special shoes to make themselves heavier.

Life on Mars will be better in many ways.       3     It is possible to live in a large building with many bedrooms. Then, robots will do most of the work, so we have more time for hobbies.

    4     Every student can study, do their homework on the computer and take exams in online schools. Each student will also have their own online teacher called “E-teacher”.

However, in some ways, life on Mars may not be better than that on the earth today.     5     Meals will probably be in the shape of pills and will not be as delicious as they are today. Also, space travel will make many people feel ill.

4 . Humans might live on another planet one day! That seemed ________ years ago. But now the idea might come true. Stephen Hawking, a great British scientist, said that we humans only have 1,000 years to live on the earth. It means that humans will ________ to another planet in 1,000 years.

In fact, we have found one red planet—Mars. Mars is the fourth planet from the sun and it’s ________ to Earth, but it’s much colder than Earth. For many years, scientists have studied Mars.

Some years ago, they ________ robots there and wanted to find water and life on Mars. ________, they found that there is water on it. Then the idea of living on Mars looks possible.

In 2013, Dutch scientists first planned to put ________ on Mars in the 2030s. They offered (提供) people one-way tickets to go and build new homes on Mars. ________ it was dangerous, over 200, 000 people still wanted to take part in (参加).

American scientists showed another plan to get humans to Mars in 2033. They are working on building larger ________ to fly to Mars these days. They are also doing a lot of preparations to help people ________ the earth.

I believe that humans will go to Mars and have an even closer look ________ our red neighbor.

5 . Have you ever seen the auroras (极光) in the sky? Cosmic radiation (宇宙辐射) creates these pretty lights in the North and South Pole areas. It seems that cosmic radiation is a beautiful gift from space. But for some people, it can be dangerous.

A 53-year-old fight attendant in South Korea, who spent about 1,022 hours flying each year, passed away due to cancer. A South Korean court connected his death to great exposure (暴露) to cosmic radiation. During his career, nearly half of his flights crossed the areas in and around the North Pole, where cosmic radiation is extremely strong.

①       Cosmic radiation from space is hitting Earth nonstop, coming from both the sun and other stars in the Milky Way.

②       Earth’s magnetic field (磁场) and atmosphere (大气层) protect us from most cosmic radiation. The magnetic field is strongest near the equator and weakest at the poles. People living at higher latitudes (纬度), like in Heilongjiang province, are exposed to a little bit more cosmic radiation than those living at lower latitudes, like in Hainan province. Also, when you go higher in an airplane, the thin atmosphere increases exposure to cosmic radiation.

③      For flight attendants crossing polar areas and for astronauts in space, cosmic radiation can create health risks. NASA reported that the radiation exposure faced by astronauts spending six months in space is the same as having 1,000 chest X-rays.

④      However, what makes cosmic radiation dangerous also makes it useful. The light speed and energy of cosmic radiation have provided wonderful ideas for treating tumors (肿瘤). Scientists can now produce man-made radiation similar to cosmic radiation. Compared to the present ways of treating tumors, it can kill tumors better with less damage to healthy parts of the body around them.

6 . Venus, Jupiter, Mercury and Saturn are four major planets in the solar system. But do you know from where their English names originated? If not, just look ahead.

7 . We have always been interested in the moon. 2, 000 years ago, people already knew it moves 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 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 the earth. This was because they believed the moon had once been a planet that had been caught in the earth’s gravity (重力) 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 the earth. They believe very early in its history, maybe 4 billion years ago, something about the size of Mars hit the 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, though our ideas about the moon may change again, we will still be interested in it.

8 . It often takes astronauts days to go to the moon. But will people live there? Will people build _______ city on the moon?

Some people think it is ________. But it won’t be easy. There isn’t ________ oxygen (氧气) on the moon. Spaceships (宇宙飞船) will need to bring oxygen from the earth. Food will be a problem, too. How will people grow vegetables? There isn’t any water, ________ scientists think that they might find some ice. The energy (能量) for the city won’t be a problem—it will come ________ the sun.

________ will go to the moon? Maybe scientists will go there. The moon is an interesting place for ________. It is never cloudy or rainy on the moon, so it is a good place ________ the stars and planets. Maybe we will build a university for them. We will probably build a hotel for ________, too. There are no beaches on the moon, but people can walk on the moon and take photos of the earth.

Will it ________ ? Maybe. But one thing is true: A visit to the moon hotel will be very expensive!