People often said Thomas Edison was the greatest genius(天才) 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 he could usefully do with them.
Edison enjoyed thinking. He knew that most people would do almost anything instead of the difficult work of thinking, especially if they do not think very often. But he knew, too, that thinking could give men enjoyment and pleasure.
Edison could not understand why anyone could not be interested in life. As he loved to think, he also loved to work. On the day he became 75 years old, someone asked him what idea he had about life. “Work,” he answered, “Discovering the secrets of nature and using them to make men happier.” He said he had enough inventions in his mind to give him another 100 years of work.
What is genius according to Thomas Edison?

A．Hard thinking.

B．Hard work.

C．Useful ideas.

D．Useful inventions.

How did Edison always deal with the secrets of nature after exploring them?

A．To write down what he had learned.

B．To carry out a new experiment.

C．To make them useful in life.

D．To share them with others.

What does the last sentence in the passage mean?

A．Edison was born to be a great inventor.

B．Edison was able to live another 100 years.

C．Edison was ready to make his 100th invention.

D．Life was too short for Edison to work for human beings.