题目

x2+ax﹣y﹣（bx2﹣x+9y+3）的值与x的取值无关，则﹣a+b的值为（ ） A．0                           B．﹣1                         C．﹣2                        D．2 答案：D 【解析】 根据整式的加减法，去括号合并同类项可得x2+ax﹣y﹣（bx2﹣x+9y+3）= x2+ax﹣y﹣bx2+x-9y-3=（1-b）x2+（a+1）x+（-1-9）y-3，由于值与x的值无关，可得1-b=0，a+1=0，解得a=-1，b=1，因此可求-a+b=2. 故选D. 点睛：此题主要考查了整式的值与字母无关形的题目，解题关键是明确无关的主要特点是系数为0，然后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（八）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：在错的词下面画一横线，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。Nowadays in China, either in the morning or after dinner, people, especially elderly woman, will gather in squares to dance with popular music. More and more young people are also participating the square dance now.There are many reasons for their popularity. First of all, China has made a great progress in the social and economic development in the past decades, and people had more time and energy to enjoy their life. Therefore, doing the square dance is a good way for people to get fit.However, dancers play loud music and take up lots of public places, where makes many people annoying. It is time that square dancers make some change.