1 . A black hole is a place in outer space with very strong gravity. Gravity is a great force（力量） that shapes the universe. On Earth, gravity makes apples fall from trees. It keeps your feet planted on the ground. The gravity in a black hole is much stronger. It is so strong that nothing around it can get away from it, not even light.

Black holes are invisible. We can’t actually see them because they don’t throw back light. But scientists can find them with space telescopes and special tools. The strong gravity makes nearby stars move in a certain way. By studying how the stars move, scientists can find out if they are flying around a black hole. Strange things happen around black holes. This makes black holes a popular subject of science fiction（科幻）stories, although they are very unreal.

A black hole forms（形成）when a star dies. The star falls in on itself and turns into a very small point. Because of its small size and huge mass（质量）, the gravity will be so strong that it will pull light in and become a black hole. Black holes can grow huge as they continue to pull other things in and “eat” them. Many scientists believe that there are super-massive black holes at the center of galaxies, including the Milky Way.

The idea of the black hole was first suggested by two different scientists in the 18th century: John Michelle and Pierre-Simon Laplace. In 1967, a physicist named John Archibald Wheeler came up with the name “black hole”. Studying black holes can tell us many things about our galaxy and help scientists answer questions about the universe.

7 . In the universe, as we all know, there are the Sun, the Moon, the Earth and many stars. Through our geography lessons, we know the Earth goes around the Sun and the Moon goes around the Earth. We have day and night because the Earth keeps turning all the time.     1     When our part of the Earth turns away from the Sun, it is night.

Just because the Moon is closer to the Earth than the Sun, it looks much bigger than the Sun.     2     And small things will also look bigger when they are nearer.

The Sun is big enough to give out very strong light.     3     Why? In fact, the light from the Moon comes from the Sun. The Moon looks much bigger and brighter than the stars. But actually（事实）the stars are much bigger and brighter than the Moon.     4    

    5     But of all the planets, only on the Earth there are living things and people can only live on the Earth, too.

8 . What is space?

Space is an exciting place! Our solar system is in space. It is mainly made up of the sun and the eight planets that travel around the sun. The solar system also has moons and other space objects（物体）.

The sun

The sun is in the center of the solar system. It is a hot and bright star. A star gives off heat and light. The sun is the closest star to the earth. That’s why it looks different from other stars. Most stars look small. We can see them only at night because they’re so far away and sunlight is so strong that we can’t see them only by our eyes.

Around the sun

A planet is a large ball made of rock or gas. We live on one of them — the earth. Each planet moves around the sun.

Around the earth.

The earth has one moon. It travels around the earth. The moon is made of rock. It is covered with many deep holes. The moon may look as if it gives off light, but in fact, it doesn’t.

9 . Wang Yaping, together with Zhai Zhigang and Ye Guangfu, went into space aboard the Shenzhou XIII on October 16th last year. And now they are preparing for their return trip in the middle of April, 2022. The 41-year-old Wang became the first female astronaut (女航天员) to enter Tiangong space station. She also became a space teacher and gave two lessons to students on Earth.

Wang’s space dream started in 2003, when China sent its first astronaut Yang Liwei into space. At that time, Wang was a pilot in the Chinese army. After having safe flights for 1,600 hours over nine years, Wang was a strong candidate to become an astronaut in 2010. She pushed herself hard, getting the same training as men. “The space environment won’t change because you are a woman,” she told Xinhua.

The hardest part is the high-G training. Sitting in a spinning (旋转的) machine, Wang would become blind for a while because her brain was short of blood. “There’s a red button (按钮),” said Wang. “If you can’t bear it, you can press it to stop.” But Wang never used it. “There is no such red button in my heart.” That strong spirit finally made her dream come true in 2013. She joined the team for the Shenzhou X mission.

Wang said that as astronauts, women have their own advantages. “Women may be more patient and can better deal with loneliness. Women’s hearts are also easier to adapt (适应) to the weightless environment, making them more suitable for long-term missions.”

Wang Yaping went a long way before becoming the first woman to enter the Tiangong space station. She sets a good example for all women who dream of going to space.

10 . If you are dreaming of becoming an astronaut after you grow up, get started now! An astronaut needs a strong body and mind. Shenzhou XIII astronauts are able to live upside-down （倒立）. They do this not just during sleep, but also when eating and going to the toilet. Before they ________ space, they had lots of practice. Each upside-down training time lasted for 20 days.

Chinese astronauts aren’t just spaceship ________ but also machine repairers（修理工）and scientists. They have to know every part of the spaceship and how it ________. If something goes wrong, they’ve got to know ________ repair it. Also they do scientific experiments in space.

Shenzhou XIII astronauts know how to live in ________. They took a knife, a gun（枪）and some dye（染色水）________ them into space. If they land in forests, the knife and gun can protect them from wild animals. If they ________ the sea, the dye can colour the seawater around them yellow. This can drive ________ sea animals away.

Shenzhou XIII astronauts can’t get dizzy（眩晕）. A spaceship is not a plane. When it ________ the extra gravity force（额外重力）can break people’s bones（骨头）.

Astronauts must have strong bodies for this. They can’t get a headache or be sick. Because they have to ________ many things. They’ve got no time for sickness. Do you still have a long, long way to go?