“价一类”二维图可表示元素化合价与物质类别之间的关系,图中a、b、c、d、e、f代表常见的含碳物质。 (1) a是沼气的主要成分,写出它燃烧的化学方程式 。 (2) 下列关于物质及其转化的说法中与事实相符的有。 A . b和d反应生成c B . d和水反应生成e C . 物质f可能难溶于水 D . 由b到f至少要经过三步反应此题要求改正所给短文中的错误.对标题号的每一行做出判断:如无错误,在该行右边的横线上划(√);如有错误(每行只有一个错误),则按下列情况改正: 此行多一个词:把多余的词用斜线(\)划掉,在该行右边横线上写出该词,并也用斜线划掉。 此行缺一个词:在缺词处加一个漏字符号(∧),在该行右边横线上写出该加的词。 此行错一个词:在错的词下划一横线,在该行右边横线上写出改正后的词。 注意:原行没有错的不要改。 Before I went to senior middle school, some people told 1. me, “the lives of a senior middle school is unforgettable.” 2. While I first entered my senior high school,everything 3 seemed unpleasant. Face all the strange things around me, 4. I often miss my old friends and classmates. I didn’t want 5. to talk with others and make friends with others. Little by 6. little, my school records went bad to worse, especially my 7. maths. I couldn’t even pass the exam. I lost the heart and 8. missed the happy times all day long. I told me, “I don’t 9. belong it. I don’t like the life here.” 10.