S3. If the temperature at the earth’s surface is 20F, the temperature in a coal mine 500 feet below the surface would be _____________________.

A．The sun.
B．The stars.
C．The mountain ranges.
D．The clouds.

A．A large number of people want to learn driving.
B．A large number of traffic accidents or deaths happened every year.
C．Road conditions are becoming complicated.
D．Traffic policemen worry too much about so many cars running on the road.