建立物流服务提供商的竞争模式，可以避免物流业务停止运行或短期内必须找到新的供应商的困难局面。
参考答案：对
计算题：已知2.5mm2的铜导体为7/7/0.25mm的同心复绞线组成，求该铜导体的外径。
Questions 1-4
According to the man, what inspired him to dedicate his life to studying dinosaurs？（）
A．His grandfather’s house.
B．His parents’ remarks.
C．A magazine.
D．A coursebook.
