Over the last few centuries, there have been many changes in our lives.

In the old days, planes were not very popular because they could be dangerous and too expensive. Nowadays, more people can travel by plane and get to the other side of the world in just one day.

When it comes to work, people had to work much harder because they did not have the useful tools and instruments that we have now. Today, however, most of the difficult and dangerous work is done by computers and machines.

Imagine people’s living conditions a few hundred years ago. There were no bathrooms or running water in many houses. People shared public bathrooms with strangers. And they had to collect water from faraway places.

Nowadays, every child has the chance to get a good education. In the past, there were fewer schools and the quality of education was much poorer. Now education is free for primary and middle school students. Also, it is much easier to find the educational materials that you need on your mobile phone or your computer instead of going to the library.

With the development of science and technology, our life is much better than it used to be. And we are continuing to create new things to make our lives better and easier.

On March 23, the Shenzhou XIII crew delivered their second science lecture, in which the astronauts also carried out experiments to show physical phenomena only possible in microgravity.

In one experiment, Wang used a toy of Bing Dwen Dwen, the popular mascot of the 2022 Beijing Winter Olympics, to display how objects fly in a weightless environment.

Before ending the lecture, the astronauts answered questions taken from members of the public and students at the ground venues. The questions covered various facts of life and work in space, such as how to take care of their skin and if the moon looks different from the Tiangong station.

At the end of the class, Wang told the audience that in the coming months, two large space labs—Wentian and Mengtian—will be launched into space to dock with the Tianhe module to complete the Tiangong station, and then China will have stronger capability in terms of space-based scientific experimentation and the “Tiangong class” will become more interesting.

Pang Zhihao, a retired spaceflight researcher, said the class will be an “eye-opener” for youngsters, specially prepared for students by implanting the pursuit of science and innovation in them.

“Many distinguished scientists were created by their interest and curiosity about ‘strange things’. The experiments done by the astronauts will put ‘question marks’ in our students’ mind, and the youngsters will then move to find answers and explore more places unknown to humankind,” he said.

You might think the 4G mobile connection on your phone is pretty fast. However, an even faster and stronger technology is just around the corner. (A) 5G networks will introduce us to a new world of connectivity.

What is 5G? It's the latest generation of mobile network technology. It works by using a wider range (范围) of the radio spectrum (射频频谱) , allowing (B) plenty of signals to be sent and received at higher speeds.

This means 5G will be super - fast. People will be able to use the internet at a much greater speed than before. 5G will increase download speeds to up to 20 Gb per second - much faster than 4G’s 1 Gb per second. That means a movie can be downloaded in just a few seconds!

5G also has less lag (延迟) time than 4G. This means your video calls and other types of communication will be more stable (稳定的) and reliable (可靠的).

Most importantly, 5G's greater network capacity (容量) means that we can connect not just people to people, but also people to machines, or to just about anything. 5G will make the "internet of things" possible, connecting all of our devices and environments to an online network.

For example, the lights in your living room, the refrigerator in your kitchen - all of (C) them can be controlled with your phone. (D) Outside of the home, factory owners will be able to use it to control their robots. Farmers could use it to follow "smart" tractors on their farms.

Wearable devices could send updates to your doctor about changes in your health. Driverless cars and home delivery drones (送货无人机) will depend on 5G to work better. A completely wireless (无线的) world in at our doorstep.