题目

将物质按照一定的规律分类研究，是常用的化学学习方法。下列各组答案中按一定依据分类正确的是（  ） A．化合物：蒸馏水、二氧化碳 B．混合物：海水、液氧、空气 C．氧化物：过氧化氢、高锰酸钾 D．非金属元素：氦、硒、汞 答案：A 【详解】 A、蒸馏水和二氧化碳都是由不同种元素组成的纯净物，都属于化合物，故A正确； B、海水中含有水和氯化钠等物质，属于混合物；液氧是由一种物质组成的，属于纯净物；空气中含有氮气、氧气等物质，属于混合物，故B错误； C、过氧化氢是由氢元素和氧元素组成的化合物，属于氧化物，高 阅读理解 　　Could you be a genius like Einstein? A genius needs to learn and think．Reading is a good idea，but it is not enough．Einstein’s advice is to use your brain more．Here are some tips： 　　●Ask．When you look at new things，ask why they are new or different．Ask ques　　tions．Ask yourself and ask others．Keep thinking until you find the answer． 　　●Draw．Einstein thought in pictures．Sometimes，it helps to draw problems and ideas． 　　●Read．Try to read new things．Read books from different parts of the library．After you read，think about the ideas you have learned．Are they different from what you thought? 　　●Relax．Many ideas come when you are relaxed．Take some time to relax yourself in the ways like taking a walk in a park，going to a concert or a museum． 　　●Write．Keep a diary．Write down your questions and ideas．Write down new ideas after you read． 　　●Share．Einstein used to talk to his friends and explain his ideas．Sometimes，a friend can help you find the answer to a problem． 　　●Be brave．Do not let other people say your ideas are silly．Explain yourself．Let other people explain why they think you are wrong．Then decide． (1) How many tips are there in this passage? [　　] A． Five． B． six． C． Seven． D． Eight． (2) What can we do to relax ourselves from the passage? [　　] A． Keeping a diary． B． Asking questions． C． Taking a walk． D． Reading new things． (3) Einstein suggested we should _________ if other people say our ideas are silly． [　　] A． discuss the ideas with others B． draw problems and ideas C． go to a museum with others D． write down your ideas (4) Which of the following is NOT true according to the passage? [　　] A． A genius needs to learn and think． B． We should find the answers all by ourselves． C． Einstein’s advice is to use our brain more． D． Einstein liked to talk to his friends and explain his ideas．