单选题 .  A land free from destruction, plus wealth, natural resources, and labor supply—all these were important     21    in helping England to become the center for the Industrial Revolution.     22    they were not enough. Something     23    was needed to start the industrial process. That "something special" was men—    24    individuals who could invent machines, find new     25    of power, and establish business organizations to reshape society.
    The man who     26    the machines of the Industrial Revolution     27    from many backgrounds and many occupations. Many of them were     28    inventors than scientists. A man who is a     29    scientist is primarily interested in doing his research     30    . He is not necessarily working     31    that his findings can be used.
    An inventor or one interested in applied science is     32    trying to make something that has a concrete     33    . He may try to solve a problem by using the theories     34    science or by experimenting through trial and error. Regardless of his method, he is working to obtain a     35    result: the construction of a harvesting machine, the burning of a light bulb, or one of     36    other objectives.
    Most of the people who     37    the machines of the Industrial Revolution were inventors, not trained scientists. A few were both scientists and inventors. Even those who had     38    or no training in science might not have made their inventions     39    a groundwork had not been laid by scientists years     40    .21.