Thomas Edison worked（）hours a day so he called himself a "two-shift man".

单项选择题Of all the inventions,（）was probably the most important for civilization.

A．the vote recorder
B．the stock ticker
C．the light bulb
D．the motion picture camera

单项选择题The main idea of this passage is（）

A．Thomas Edison was always interested in science and inventions, and he invented many important things
B．Thomas Edison could not keep a job
C．Thomas Edison worked day and night on his experiments
D．deaf people make good inventors because they can focus without the distraction of spoken conversation