Crew members of Shenzhou XII mission gave a science lecture（讲座）400 kilometers above Earth to millions of students on Thursday afternoon, December 9, 2021 in the Tiangong space station.

The three astronauts Zhai Zhigang, Wang Yaping and Ye Guangfu greeted students, teachers and other viewers when the lecture started in the afternoon. They explained their life and work inside the space station.

The astronauts made scientific experiments to display interesting physical phenomena（现象）in space, for example a “water ball”. They also invited young viewers to do similar experiments along with them to see the differences between space and land environments to experience the fun of exploration. Besides, they answered questions from students during the lecture.

Tens of millions of teachers and students across China, including Hong Kong and Macao watched the hour-long televised event. They were excited to have such a chance to understand more about biology, physics and chemistry through the experiments in space.

The activity showed the nation’s technology development, and our students have learned some new things that we could not teach in a class. It was the first lecture of the Tiangong Class and more lectures will be held. Such activities will help spread knowledge about space and increase the love for science among young people.——Rinchen Drolkar, a teacher

The astronauts’ experiments really surprised me. I would like to take part in our country’s space exploration program in the future——Wang Yihan, from Xizang 5th-grade student

English words like other languages change all the time. People need new words for new ideas and inventions. Different words come into use and older words are used in a new way. Here are some ways to change.

English words can change by borrowing words from other languages. The word “tomato” was from Mexico, and “tea” came from China. Now new words are made by joining two words together. “Weekend” and “cookbook” are examples. A latest one “brunch” comes from breakfast and lunch. Do you have brunch every day? Sometimes new words are shorter forms(形式) of the longer words. For example, the word “photo” was from “photograph” by cutting off the end of the longer words. The names of people and products(产品) can also become new words. Our food “sandwich” was from a man called Sandwich.

Can you find any other examples for each of these ways to make new words?

In many countries, people are encouraged to buy electric cars. It is said that driving an electric car is good for the environment. But is that true? The University of Minnesota recently studied emissions (排放物) from different cars. The scientists found that sometimes, electric cars are more harmful than petrol (汽油) cars.

Surprising? Well, please pay attention to the word “sometimes”. Electric cars are supposed to be clean. The problem lies in the power that is used to charge them. If the power comes from wind or solar energy, electric cars will cause little pollution. However, if the power is produced from coal, they will be very harmful. According to the study, emissions from these cars kill about 3,000 people a year. However, pollution caused by petrol cars only leads to 880 deaths a year.

In fact, sales people are not lying when they say electric cars are clean. However, they are right only when the power used to charge their cars is also clean.

So how clean electric cars are depends on what its electricity comes from. In France, more than half of the power comes from nuclear (核) stations. Electric cars there should be as clean as they are marketed to be. In many developing countries, however, electricity mainly comes from coal. India, for example, depends on coal for 61 percent of its power. Only two percent of electricity comes from nuclear energy. In countries like India electric cars are not clean at all.