Mr.Smith used to be in prison for three____(year),which may make you think he is not a good man.But____fact, he is kind-hearted as well as honest.The reason why he was put into prison was not that he____(he) broke the law, but that his six-year-old son blew up the bridge near his home,imitating（模仿）what he had seen on TV.Although this little boy____(break) the law,he was so young that he couldn't be put in prison.According to the local law,the boy's parents could not avoid____(punish).

    As____result, Mr. Smith received the punishment. He was arrested and finally was taken to the police station. Most of the people in the town showed pity on him,but it was____(complete) useless.After all,everybody is to obey the law____(make) by the government.Unluckily,what made us____(amaze) was that Mrs.Smith was out of work before long.However, they have lived a happy life ever since.Misfortunes（不幸）tell us____fortune is.

操作步骤如下：

第一步：计算这个数与1的和的平方，减去这个数与1的差的平方；

第二步：把第一步得到的数乘以25；

第三步：把第二步得到的数除以你想的这个数．

下列有关化学用语表示正确的是（　　）

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