题目

 Amy makes fewer mistakes than Frank. She does her homework ____.             A. more carefully                                       B. more carelessly             C. more careful                                          D. more careless 答案：A    考查副词比较级。carefully修饰动词does，由于两者之间进行比较需用比较级， carefully是多音节词，用more carefully。故选A。 实数a在数轴上的位置如图所示，化简＝________．