阅读理解
His name was Fleming, and he was a poor Scottish farmer. One day late in the afternoon, while working to support his family, he heard a cry for help coming from a nearby pond(池塘). He dropped his tools and ran to the pond. There, up to his neck in the water, was a terrified boy, crying and struggling to free himself. Obviously the boy did not know how to swim. Fleming jumped into the pond and quickly swam toward the boy. He saved the boy who could have been a terrible death.
The next day, a very cool carriage pulled up to the Scotsman's house. A well-dressed noble man stepped out and introduced himself as the father of the boy Fleming saved the day before.
“I want to repay you,” said the nobleman. “You saved my son's life.”
“No, I can't accept any payment for what I did,” the Scottish farmer replied, waving off the offer.
At that moment, the farmer's own son came to the door of the farm house, confused by who was visiting them.
“Is that your son?” the nobleman asked.
“Yes,” the farmer replied proudly.
“I'll make you a deal. Let me take him with me. I promise you that I will give him a good education. If the boy is anything like his father, he'll grow up to be a man you can be proud of.”
And he did. In time, Fleming's son graduated from St. Mary's Hospital Medical School in London and went on to become a famous doctor.
Years later, the nobleman's son became seriously ill. Who saved him? The farmer's son did.
It's important to help people no matter how successful you are in life. You never know when you are going to be the one who needs the help.
=" " （ ）
Rn放出α粒子后变成钋核
Po，α粒子动能为Eα.若衰变放出的能量全部变为反冲核和α粒子的动能，真空中的光速为c，则该反应中的质量亏损为( )