题目

Amy has to look after her sister on Sundays. (改为否定句)Amy______to look after her sister on Sundays. 答案：【答案】doesn’t have【解析】句意：艾米星期天得照顾她妹妹。根据题意是变成否定句，这里是一般现在时态，含有情态动词have to，主语是第三人称单数，变成否定句要借助助动词does+not+动词原形。故答案为doesn’t have。已知二次函数f（x）=ax2+（2a-1）x+1在区间[-32，2]上的最大值为3，求实数a的值．