改错题。
For different reasons，people are pouring into big cities，which cause much more trouble
than expected.As the growth of the population，city problems are grown day by day.To begin
with，big cities are becoming so crowded that it makes find jobs very difficult.As a result，
people without jobs are likely to become danger to our society.In additional，the environment
is getting worse and worse，but there is pollution and traffic problems as well as.We can’t
choose but face with them.In my opinion，big cities need to control the population to help
develop itself for the future.In terms of improving the environment, every citizen should be
called on to contribute to protect the environment.