题目

下列关于甲、乙、丙、丁四种有机物说法正确的是(     ) A．丁属于芳香烃 B．四种物质中加入NaOH溶液共热，然后加入稀硝酸呈酸性，再滴入AgNO3溶液，均有沉淀生成 C．四种物质中加入NaOH的醇溶液共热，然后加入稀硝酸呈酸性，再滴入AgNO3溶液，均有沉淀生成 D．乙发生消去反应得到两种烯烃 答案：【答案】B 【解析】 试题分析：A、丁中含有溴元素，不属于烃类，故A错误；B、卤代烃和NaOH的水溶液发生取代反应生成HX，HX和HNO3酸化的AgNO3溶液发生复分解反应，甲、丙生成白色沉淀，乙和丁生成淡黄色沉淀，故B正确；C、甲、丙、丁不能发生消去反应生成HX，所以甲、丙、丁和氢氧化钠的醇溶液共热Fill in each blank with a proper word beginning with the given letter. 　　Do you live in a city? Do you know h________ cities began? Long ago, the w________ had only a few thousand people. These people m________ from place to place, They moved over the mountains, hunting a________ for food. 　　No one knows how or when these people learned about growing food. But when they did, their lives c________. They did not have to l________ for food any more. They could s________ in one place and grow it. 　　People began to live near one another. So the first v________ were formed Many people came to work in the villages. The villages grew very big. 　　When m________ appeared, life in the villages changed again. Factories were built, more and more people began to live near the factories. Cities began to come into being.（形成） 　　Today, some people are moving back to small villages, Can you tell w________?