题目

阅读理解;阅读A、B两篇短文，从每小题所给的四个选项中，选出能回答所提问题或完成所给句子的最佳答案。     Millie is a little girl who is at the age of nine. She is a pupil in a primary school. She works hard at her subjects. In class, she takes an active part in all kinds of activities. She looks smarter than her classmates.     One day, she was doing her homework after supper as usual. Her father was not in. Her mother was taking a shower in the bathroom. After she finished her homework, Millie asked her mother to check it for her, but he现有下列算式：其中错误的有（　　）（1）2a+3a=5a（2）2a•3a=5a2（3）ax（﹣1﹣a2﹣x）=ax﹣a3x﹣ax2（4）（x4﹣x3）x2=x6﹣x5A．1个B．2个C．3个D．4个