reaction．
Question 21-25 are based on the following passage：
Successful innovations have driven many Older technologies to extinction and have
resulted in higher productivity，greater consumption of energy，increased demand for raw
mateials，accelerated flow of materials through the economy and increased quantities of
metals and other substances in use per person．The history of industrial development is fUll of
examples．
In l870，horses and mules were the prime source of power on U．S．farms．One horse or mule was required to support four human beings——a ratio that remained almost constant for many decades．At that time，had a national commission been asked to forecast the horse and mule population for 1970，its answer probably would have depended on whether its consultants were of an economic turn of mind．Had they been“economists”，they would have recognized that the power of steam had already been harnessed to industry and to land and ocean transport．They would have recognized further hat is would be only a matter of time before steam would be the prime source of power on the farm．It would have been
difficult for them to avoid the conclusion that the horse and mule population would decline
raPidly．
21. Which of the following is NOT mentioned by the author as a consequence of new
technological developments？
A．Older techologies die away.
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