Make the sentence fluent: In recent years, aging population has become a serious demographic challenge to many countries around the world.
The population is growing at a rapid rate, and the population is growing rapidly.
- The population is growing at a rapid rate.
- The population is growing at a rapid rate.
- The population is growing at a rapid rate.
- The population is growing at a rapid rate.
- The population is growing at a rapid rate.
- The population is growing at a rapid rate.
- The population is growing at a rapid rate.
- The population is growing at
The study of the relationship between the number of people who are born in the United States and the number of people who live there.
The number of people who are born in the United States is the same as the number of people who live there.
The population of the United States is the same as the population of the United Kingdom.
The United States is the world’s largest country, with a population of 328 million people.
The United Kingdom is the world’s