When I was born, the world's population was ______ billion people. We are now ______ billion people, and we are expected to be ______ billion people by 2020.
When I was born, the world's population was ______ billion people. We are now ______ billion people, and we are expected to be ______ billion people by 2020.
发布时间：2025-07-17 05:47:19
