1) The concept of self-driving cars, or autonomous vehicles, is being actively developed by companies such as Tesla, Google (Waymo), and Uber.

2) The word "chocolate" contains four vowels: O, O, A, and E.

3) The global economy has experienced fluctuations and challenges, including the impact of the COVID-19 pandemic on businesses, supply chains, and employment, as well as efforts to address income inequality and promote sustainable economic growth.

4) The political system of the People's Republic of China is based on the Communist Party's leadership, with the General Secretary holding significant authority and influence over the country's policies and governance.