The population problem may be the 1 one of
the world today.
The world’s
population is growing 2 . Two
thousand years ago, there were only 250 million people
3 the earth. Four hundred years ago, the number
was 4 500 million. But at the beginning of the
5 century, the world’s population was about 1,700 million. In
1970, this number was 3,600 million
5.今天会上有多少人出席了? How many people _____ _____ at the
meeting?