A．In regard to hydroelectric power, Japan is lucky to have abundant rainfall and dense concentration of population.
B．No other countries in the world have developed their resources of hydroelectricity to such an extent as Japan.
C．Some other Asian countries have also develop their resources of hydroelectricity.
D．Japan developed their resources of hydroelectricity greatly compared with America.

A．when the steam engine was invented, it soon replaced water as a source of power, so water was useless for a certain period
B．Factories could be built far from coal fields, because coal is portable
C．It was convenient to build a factory in the coal fields
D．Japan is a country that relies on hydroelectric power