I do every single bit of housework ______ my husband Bob just does the dishes now and then. A.since B.while C.when D.as 答案:B 解析: 略二次函数y=ax2+bx+c的自变量x与函数值y的部分对应值如下所示,相应图象如图所示,结合表格和图象回答下列问题:【小题1】抛物线y=ax2+bx+c的对称轴是直线x= ;【小题2】方程ax2+bx+c=0的两根是x1= ,x2= ;【小题3】求出二次函数y=ax2+bx+c的解析式及m的值;【小题4】求当方程ax2+bx+c=k有解时k的取值范围.(结合图形直接写出答案)