威尔逊指出行政研究建立的基础为（）
A.管理
B.法律
C.经济
D.政治
参考答案：A
I called Hnnah many times yesterday evening, but I couldn’t get through. Her brother _____on the phone all the time!
A．was talking
B．has been talking
C．has talked
D．talked
机床工作时发生振动有何危害
