题目

用适当的化学用语填空： （1）两个亚铁离子 ；  （2）3个氧化钠分子 ； （3）纯碱 ；        （4）含氯元素的氮肥 ． 答案：【考点】化学符号及其周围数字的意义． 【专题】化学用语和质量守恒定律． 【分析】本题考查化学用语的意义及书写，解题关键是分清化学用语所表达的对象是分子、原子、离子还是化合价，才能在化学符号前或其它位置加上适当的计量数来完整地表达其意义，并能根据物质化学式的书写规则正确Long ago there were two people--- a young father and an old neighbor. One day the young father was visiting the old neighbor. They were standing in the old man’s garden, talking about children. The young man said, “How strict should parents be with their children?” The old man pointed to a string（绳子）between a big strong tree and a thin young one．“Please untie（解开）that string，” he said．The young man untied it, and the young tree bent over to one side. “Now tie it again，please,” said the old man, “but first pull the string tight so that the young tree is straight again.”The young man did so．Then the old man said，“There，it is the same with children. You must be strict with them, but sometimes you must untie the string to know how they are getting on．If they are not yet able to stand alone，you must tie the string tight again. But when you find that they are ready to stand alone，you can take the string away.”【小题1】The story is about ＿＿＿＿＿＿＿ ．A．how the young father should get on with his old neighbor B．how to tie and untie the string C．how to take care of young trees D．how strict parents should be with their children. 【小题2】The young man untied the string ＿＿＿＿＿＿＿ ．A．only to find that the thinner one bent over to one side B．in order to let the old man teach him C．in order to throw it away D．so that both of the trees would grow straight 【小题3】When can the string be taken away？＿＿＿＿＿＿＿ ．A．When the young man has untied it next time B．When the young tree grows strong enough C．When the old man has left D．After you have untied it 【小题4】At last the old man told the young man ＿＿＿＿＿＿＿ ．A． that he should be strict with his children if they could not yet stand alone B．that he should be hard on them C． that he should tie his children until they are ready to stand alone D．that he should always be strict with his children