——Jenny, ________do you visit your grandparents?——Twice a month.
A:How long
B:How soon
C:How often
D:How many
二次函数y=2(x﹣1)2+3的图象的顶点坐标是____ .
蝗虫是比较常见的昆虫,它危害玉米、高粱和水稻等多种农作物,是有名的农业害虫。蝗虫的呼吸是靠 ( )