We didn't now how to clean up pollution and trash. Another one is we burn too much fossil fuel.
network
The most intractable challenges of the 21st century.
there are problems
am, göt ve meme.
Some of the challenges of the 21st century include climate change, income inequality, global health issues, and technological disruption. These challenges require international cooperation, innovative solutions, and long-term planning to address effectively.
21st century.
We are in the 21st Century.
It is in the 21st century.
the 21st century
~this is the 21st century
Yes they do have batteries in the 21st century and had in the 20th century.
No, there is no apostrophe in the phrase "21st century."