某公司每年购买原材料300万元，卖方提供的信用条款为“2/10，N/30”，公司总是在折扣期内付款，设一年有360天，问商业信用的成本是多少？若公司将其付款期延长到40天，放弃现金折扣的成本又为多少？
Which tools on Cisco.com could you use to plan for correct Cisco lOS images to support a customer’s security design and requirements？ （Choose two.）（） [" Cisco lOS Matrix Navigator"," Cisco Feature Navigator"," Cisco lOS Package Planner"," Cisco lOS Security Planner"," Cisco Dynamic Configuration Tool"]
李斯特的保护贸易政策主张是（） ["重金主义","保护幼稚工业理论","超保护贸易","自由贸易论"]
C220的PON口的发射光波长是（） ["1310nm","1490nm","990nm","1530nm"]
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冷油器的换热效率主要有哪些因素有关？
