腰椎牵引时产生摩擦力的重量约为人体体重的()
A．40%
B．50%
C．60%
D．70%
E．80%
参考答案：B
In relation to agency law, explain:
(b) The potential liabilities of the principal and the agent, including both disclosed and undisclosed agents. (7 marks)
不得开办娱乐场所或者在娱乐场所内从业人员有那些？
