Communications technology plays a key role in people's lives. Evolving from the electric telegraph invented in the 19th century, our communications technology has made great achievements. We have now 1)____ from 1G to 5G. China's 5G technology is currently leading the world. With fast and stable 2)____, 5G can be applied in various scenarios. The BeiDou Navigation Satellite System is one of the four Global Navigation Satellite System providers. It is independently constructed and 3)____ by China and can be integrated with 5G to serve several fields. Transmitting signals via satellites, BeiDou makes it possible for us to send and receive messages in sparsely 4)____ areas. So it can satisfy the demand for emergency communication and search and 5)____ work. Thus, the application of information and communications technology not only changes people's lifestyles, but also turns out to be life-saving.