中枢神经系统包括（）
A.脑
B.躯体神经系统
C.脊髓
D.自主神经系统
参考答案：A, C
My Old Classmate also mentioned some important events that _______ from 1993 to 2013.
A．had happened
B．was happened
C．happened
D．has happened
简析《静静的顿河》的主要思想内容。
