农村和城市郊区的土地一般属于农民集体所有,即除法律规定属于国家所有的以外,都属于农民集体所有。( )
参考答案:对
20.He took much pain-killer last night, thus ______ his headache.
A.relieving
B.to relieve
C.relieve
D.relieved
简述专家系统设计的基本结构。