题目

若a=(-4,3),b=(5,6),则3|a|2-4a·b等于(    )A.23                  B.57                 C.63                   D.83 答案：解析:|a|2=(-4)2+32=16+9=25,a·b=(-4,3)·(5,6)=(-4)×5+3×6=-2.∴3|a|2-4a·b=3×25-4×(-2)=83.答案:D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限一词;2.只允许修改10处，多者（从第11处起）不计分。Three years ago, I went to a boarding school. The reason for my attended such a school was that my parents was very busy. They often went abroad on business but had no time to take care of myself. Besides, they thought I ought learn to be independent. Honest speaking, the school life does benefit me a lot. I not only learned some ways to solve problem on my own but also learned how to get along with others. But that I treasure most now is the friendship that I developed into at that time. How I miss that wonderful time!