判断组织兴奋性高低的简便指标是()
A、阈值
B、阈电位
C、刺激的最短时间
D、刺激的频率
参考答案：A
A．He has ever visited no more than two cities.
B．He has made only a few business trips.
C．He has never been to Shenzhen and Beijing.
D．He has been to many small cities.
代维雇佣车辆的管理和使用由（）负责。
A、代维方
B、雇主
C、司机本人
