皮质肾单位的结构特点之一是
A．分布于内皮质层B．人球小动脉口径比出球小动脉粗C．髓袢很长D．含肾素颗粒较少
参考答案：B
Passengers are permitted ______ only one piece of hand luggage onto the plane.
A．to carry
B．carrying
C．to be carried
D．being carried
简述宪法的特征。
