3 . Now the world’s population is growing faster and faster. There will soon be no room on the Earth for more people, so more and more countries, including China, send spacemen to develop the space as human’s second home in the future.

But space is not only amazing but also dangerous. While working in space, spacemen are facing danger as well as success.

Scientists have found out that radiation is the greatest danger to spacemen in space. When spacemen are working in space, they are in danger of radiation from the Sun and other stars, which is bad for their health.

Space junk is also thought to be a great danger to spacemen. It’s reported that there are 9,000 man-made things flying in space. About 30% of these are satellites, 10% are spaceships, and the rest are space junk. These junks are flying in space. They may knock against spaceship windows and do some damage. Scientists are watching and reporting any possible danger all the time. They are working on helpful ways to deal with space junk.

So we should care for space and do something to help improve the space environment.

4 . The Sun offers us light.     1     It makes things grow. All the living things on the Earth need the Sun. However, how much do you know about the Sun?

The Sun is a huge star.     2     In the sky, there are thousands of stars like the Sun. They are as large and hot as the Sun. At night, you can see many stars.     3    

Our Earth is cool enough to live on because the hot Sun is so far away.     4     If a plane flew day and night without stopping, it could take nearly 18 years to get to the Sun. If the Sun were much nearer, our Earth would be too hot to live on.     5     Aren’t we lucky to be just about the right distance away form the Sun?

6 . As space science develops, man has learned more and more about space. Space is not only amazing but also dangerous. While working in space, spacemen are facing danger as well as success.

Scientists have found out that the radiation（辐射）is the greatest danger to spacemen in space. When spacemen are working in space, they are in danger of the radiation from the sun and other stars, which is bad for their health. The harm of the radiation won’t be found until their children even grandchildren are born. Some special medicine may work a little, but no really effective（有效的）medicine has been found so far.

Space rubbish is also thought to be a great danger to spacemen. It’s reported that there were 9,000 man-made things flying in space. About 30% of these are satellites, 10% are spaceships, and the rest are space rubbish. An explosion（爆炸）in space in 1999 made a cloud of 300,000 fragments, each at least 4mm in size. A small piece of these even knocked on a spaceship window and caused some damage（破坏）.

Scientists are watching and reporting any possible danger all the time. They are working to deal with space rubbish. Although space is really dangerous, it interests many people on the earth. In the near future, it may become possible for people to spend a few days in a space hotel. We may even choose to leave the earth and live in space in a few years. So we should do something to help improve the space environment.

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7 . A group of scientists discovered a gas called phosphine(磷化氢) on Venus(金星). That means there may be living things on the planet, which made many people start to imagine the talk between aliens and humans. A reporter from Washington Post wrote a letter to people of Earth on behalf of(代表) the citizens on Venus.

There are many people in the world now. There will be a lot more people next century. So the earth will be very (1) ________ and there will be a little room for each person. (2) Maybe there will be only standing room on the earth in 600 years. (3) It will be a very serious problem. So man is thinking of a way to solve the problem.

The moon is the satellite (卫星) of the earth. Man will probably go to live there some day. But there is no air, no plants, and no life on the moon. So scientists are doing all kinds of experiments. They have to (4) ________ (solve) many problems till man can live on the moon. (5) Our dream will come true one day, we all think.

Thousands of years ago, Chinese poet Qu Yuan wrote the poem Tianwen, meaning Quest for Heavenly Truth. He came up with a series of questions about the sky, stars, nature and the world around us. The poem showed his spirit of finding the truth.

Inspired (激励) by the great poet, China named its latest series of planetary exploration missions (行星探测任务) after the poem in 2020. The first one in the series — a Mars exploration mission — has been named Tianwen 1, the China National Space Administration (CNSA) said on April 24^th, 2020, China’s Space Day. This shows China’s wish to explore the universe.

China has made great progress in space exploration. In 1970, China sent its first man-made Earth satellite (卫星), becoming the fifth country in the world to send a man-made satellite independently. Since 2003, China has carried out six Shenzhou manned missions. China’s moon exploration missions — the Chang’e series — started in 2007. In December 2018, China became the first country to send the probe (探测器) Chang’e 4 to the moon’s far side.

The Tianwen series will follow the Shenzhou and Chang’e series and move further into space. The first step is to send a Mars probe this year, which will mean the start of China’s exploration of the red planet. The probe is planned to circle around, land on and explore Mars in one mission. If it succeeds, it will be the first to finish all of these tasks in one mission. The Long March 5 rocket will send the probe to Mars.

After this mission, China plans to visit Mars again in 2028, aiming to collect soil from the ground of the planet and bring it to Earth. Around 2030, China will explore Jupiter and several small planets.