A:Just tell him to take it easy.
B:What’s the matter with him?
C:He is absent.
D:What? Where is he?
下列有关人类反射知识的描述错误的是( )
904÷18=
☆604÷21=
684÷57=
脑和脊髓组成人的中枢神经系统,其中大脑是脑的重要组成部分,大脑表面的____ 内有多种生命活动的功能区。