根据短文意思及所给单词的首字母写出所缺单词，使其意思通顺、语法正确。要求写出完整单词。（每空限填一词）

Did Thomas Edison really invent the light bulb? The answer is no. The real i of the light bulb was Joseph Swan. He invented the electric light bulb in 1860. But Swan's light bulb could not glow（发光）for a long e time to be useful.

Ten years later, Thomas Edison decided to improve on Swan's light bulb. He did a lot of experiments to find a better bulb wire. Finally, he f the right one. It could glow for about 1,200 hours and, at the same time, it was cheap. In the 20^th c, light bulb began to be widely used all over the world. Even street lamp began to use light bulbs i of oil. Since then, the light bulb has helped humans see things clearly anytime. It is one of the greatest inventions in history.