A:f′(x)=4πx
B:f′(x)=4π2x
C:f′(x)=8π2x
D:f′(x)=16πx
我们生活中常常都提到像:①小孔成像,②平面镜成像,③放大镜成像,④银幕上的像,⑤哈哈镜中的像,其中( )
My father ________in the morning , but now he likes running in the evening.
多边形的外角和等于( )
How are you going to become a(n)____ ____