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更多“Spark生态系统是什么()。”相关的问题
听力原文： Lightning is a flow of electricity formed high above the earth. A single flash of lightning 1.6kilometers long has enough electricity to light one million light bulbs.
The American scientist and statesman, Benjamin Franklin, was the first to show the connection between electricity and lightning in 1752. In the same year he also built the first lightning rod. This device protects buildings from damage by lightning.
Modem science had discovered that one lightning contains over 15 million volts. A spark between a cloud and the earth may be as long as 13 kilometers, and travel at a speed of 30 mil lion meters per second.
Scientists estimate that there are about 2,000 million flashes of lightning per year. Lightning hits the Empire State Building 'hi New York J0 to 48 times a year. In the United States alone it kills an average of one person every day.
The safest place to be in case of an electrical storm is in a closed car. Outside one should go to low ground and not under a tree. Also, one should stay out of water and away from metal fences. Inside a house, people should avoid opening doorways and windows and not touch wires or metal things.
(30)
A．Benjamin Franklin's life.
B．Lightning electricity.
C．The lightning rod.
D．The Empire State Building.
"Spark" in the sixth Paragraph means______.
A．cause
B．flame
C．burn
D．reason
