—Bill didn't go to school this morning, did he?
—_______. Though he was not feeling very well.
A:No, he didn't
B:Yes, he did
C:No, he did
D:Yes, he didn't
图中箭头表示空气运动的方向,读图完成下题.
①画出与△ABC关于y轴对称的△A1B1C1,求点C1的坐标。
②以原点O为位似中心,在第四象限画一个△A2B2C2,使它与△ABC位似,并且△A2B2C2与△ABC的相似比为2:1.
数列{an}中,an=-n2+11n,则此数列最大项的值是____.