Benjamin Franklin was a famous American inventor and scientist. 

One day, when it was 1 , he said to his son, "William, will you 2 me do something? I can't do it myself."

All right, but how can I help you? It's raining so hard," asked William. "3 are you working on now?"

"I'm very sure that lightning and electricity are 4 , but I need to do something to prove (证明) it."

"How can you do that?" William asked.

"If we fly a 5 in the coming thunderstorm, maybe we can see an electric spark(火花). If we do, we'll know the 6 is coming right out of the clouds."

His son 7  and both the father and the son went out in the rain. They flew their kite in the thunderstorm and put a 8  to the end of the wire. When the kite flew into a dark 9 , the key made electric sparks. This was what he hoped for. For the 10  time he showed people around that lighting and electricity are the same.