下列四种抽样方法,抽样误差最大的是()
A.系统抽样
B.整群抽样
C.单纯随机抽样
D.分层抽样
E.其他
参考答案:B
After his journey from abroad, Richard Jones returned home, _______.
A.tired
B.tiring
C.being tired
D.having been tired
1台局部通风机可同时向两个同时作业的掘进工作面供风。