Charles Dickens_________ many wonderful characters in his novels.

A．To illustrate that man can make use of sources of energy from the sea.
B．To show that a steamship is better than other kinds of ships.
C．To argue that man should use steamships.
D．To indicate that it is warmer in the ocean than on land.

A．the agriculture revolution
B．the invention of labor saving machinery
C．the development of scientific agriculture
D．the farming machinery in America