Scientists are very interested in the universe, and they always want to know more about it. Years ago they knew many things about ________ moon. They knew how big it was and how far ________ was from the earth. ________ they still wanted to know more. They thought ________ the best way was to send men to the moon. The moon is about 384,000 kilometers away from the earth. A common plane ________ fly to the moon because the ________ reaches only240 kilometers away from the earth. But ________ can fly even when there is no air. That is the rocket(火箭).

How can a rocket fly? If you want to know, get a balloon(气球) and then blow it up until it is quite big. Do not tie up (捆绑) the neck of the balloon, but let it go! The balloon will fly off through the air very quickly. It ________ wings(翅膀) like a plane.

There is gas(气体) in the rocket so it can fly out into space. Rockets with men in them ________ the moon. Several rockets, without men in them, have been sent to other place much farther away than the moon. One day, rockets ________ go to any place in space.

Except Pluto, there ______ eight planets in the solar system now, including Earth. By the distance from the Sun from close ______ far, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Pluto used to be known as the ______ planet in our solar system, and the furthest planet from the Sun. Pluto ______ in 1930, and was named by an eleven-year-old girl from England. Pluto is only half as ______ as the United States. This planet takes 248 earth years ______ around the sun. It means we need 6.5 earth days to ______ a day on Pluto. Pluto is about 40 times farther from the Sun than Earth is. Pluto is in an area of space called the Kuiper Belt ______ has thousands of small, icy objects. The temperature on Pluto is ______ low that Earth air would turn into ice soon. The gravity on Pluto is less strong than ______ on Earth. So fat persons may prefer to move there, they would weigh much less on Pluto.

【推荐3】“Hello, everyone! Welcome to Tiangong Class.” With this greeting, a special lecture began _____ Tiangong space station on Dec 9.

Lasting for about _____ hour, the space lecture was broadcast live to the students. “Three astronauts from the Shenzhou XIII crew — Zhai Zhigang, Wang Yaping and Ye Guangfu — hosted the lecture, showing _____ there and doing some interesting experiments that can only _____ in space. This is the second live space lecture in China. In 2013, with the help of other Sheinzhou X crew members, Wang decided _____ a speech to over sixty _____ schoolchildren across China.

Compared with the class eight years ago, this year’s space lecture is greatly different. According to Pang Zhihao, a Beijing-based space expert, the “classroom” is much _____. Instead of Tiangong I experimental module, this year Wang delivered the space lecture in the Tianhe space core module (核心舱) which is the biggest spacecraft developed by China.

Eight years ago, Wang _____ students the laws of physics and focused on the interesting phenomenon (现象) of weightlessness (失重) in space. _____ this year, biology was added. The astronauts compared the growth and shape of cells in artificial gravity (人工重力) and zero gravity in order to study their changing rules and mechanisms (机械装置).

“The spirit of science in the youth is an important driver of the progress of mankind,” Zhou Jianping, designer-in-chief of China’s manned space program; added. “Space activities can help _____ build the spirit of pursuing science and facing challenges.”