题目

利用核磁共振技术测定有机物分子结构的研究获得了2002年诺贝尔化学奖。在有机物分子中，不同氢原子的核磁共振谱中给出的峰值不同，根据峰值可以确定有机物分子中氢原子的种类和数目。例如二乙醚的结构简式为：  CH3—CH2—O—CH2—CH3其核磁共振谱中给出的峰值（信号）有两个，如下图所示： 下列物质中，其核磁共振氢谱中给出的峰值（信号）只有一个的是A．CH3CH3      B. CH3COOH          C.CH3CHO           D. CH3CH2OH 短文改错假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。增加：在缺词处加一个漏字符号(∧)，并在其下面写出该加的词。删除：把多余的词用斜线(＼)划掉。修改：在错的词下划一横线，并在该词下面写出修改后的词。注意：1.每处错误及其修改均仅限一词；2.只允许修改10处，多者(从第11处起)不计分。what would you do if you fail? Many people may choose to give up. whatever, the surest way to success is to keep your direction and stick to your goal.In your way to success, you must keep your direction. It is just like a lamp, guide you in dark and helping you to overcome obstacles . Otherwise, you will easily get lost and hesitate to go ahead.Direction means objectives. You can get anywhere without an objective in life. You can try to write your objective on paper and made some plans to achieve them. In this way, you will know what to arrange your time and to spend your time proper. And you should also have belief you are sure to succeed as long as you keep your direction all the times.