4.(★★★★★)The main idea of this passage is
________.
A.when the Internet came into
being B.how
Tim Berbers-Lee formed W3C
C.why computers develop so
rapidly D.how
the World Wide Web started
E
Reducing the use of cars
during rush traffic hours will make the environment more
livable.Unfortunately,our present living and working environments encourage the
use of cars.But,the car is taking us down the road in lower-quality air.The
exhaust(废气) from cars:
-damaging the earth’s protective ozone layer and helping to
cause the global warming;
-causes as much as 50% of the
smog-producing compounds and chemical rain in our atmosphere;
-causes 60% of the carbon monoxide in our
atmosphere.
When you consider that the
average person breathes in 9 000 quarts of air a day,you realize how important
clean air is to human being.
The government has spent
billions of dollars to control car pollution.Yet,some big cities are still in
violation(侵害) of public health standards
that protect people from breathing poisonous air.The health care costs related
to unclean air are huge.
The traditional way of
cleaning up what comes out of tailpipes has not done the job of getting rid of
automobile emissions(散发物).Yet today’s cars produces far less pollution than
models from the 1960’s.But there are now almost 51
million more cars on the road than there were in 1960,and drivers are traveling
many more miles.As a result,cars are still the single largest source of city
pollution today.
If we are going to achieve
clean air,we need to discourage car use by individuals,especially during rush
driving hours.
At the same time we reduce car
use,we must also improve our public transportation system.If going to and from
work by public transportation was convenient and cheap,people would use the
system instead of using cars to drive to work.
Yes,it will cost money to
improve our public transportation system.But we now spend billions each year in
controlling car emissions without much success.Giving some of that money to
public transportation would be a small price to pay for cleanest air.
Unless we do something to
reduce car use and get people to use public transportation,our love affair
with the car will be the death of our environment.