If the temperature at the earth's surface is twenty degrees Fahrenheit, the temperature in a coal mine 500 feet below the surface would, in degrees, be _____________.

A．not determined
B．the great pressure of the earth
C．radioactive elements
D．the heat remaining from the formation of the earth

A．the trends of the 1990s in computer industry
B．the accelerating demands for software and service
C．computers industry's close link with auto-industry
D．the trends in the peripherals arena in the next decade