Fix grammar errors in this sentence: As time gradually goes by, the population density of many countries increased.
The population of, which is the largest city in, is 1,000 people.
The population of, which is the largest city in, is 1,000 people.
The population of, which is the largest city in, is 1,000 people.
The population of, which is the, is 1,000 people.
The population of, which is the, is
The population of, which is the largest city in, is 1,000 people per square kilometer.
The population of, which is the largest city in, is 1,000 people per square kilometer.
The population of, which is the largest city in, is 1,000 people per square kilometer.
The population of, which is the largest, is 1,000 people per square kilometer