题目

People often said Thomas Edison was the greatest genius of his age．There are only a few men in all of history，who have changed the lives of other men as much as the inventor of the first useful electric light．But Edison could never be pleased only because someone said he was a genius．There is no such a thing as genius， Edison said．He thought what people called genius was mostly hard work． But Edison was a thinker as well as a worker．From his earliest days as a child he wondered about the secrets of nature．He tried to understand them，and then he tried to learn what h两台机器的功率比为3：4，它们做同样多的功所需要的时间之比为    ；在相同的时间所做的功之比为    ．