边际贡献=利润减去（）
A.固定资产
B.变动成本
C.变动制造费用
D.固定制造费用
参考答案：A
The police wanted to get clear of the reason for the accident, but all the people on the spot
remained ____. [ ]
A. quiet
B. calm
C. secret
D. silent
咳嗽反复发作五年，气短而喘，胸闷。吐痰量多白粘，神疲食少，舌淡胖，苔白腻，脉弱。此证为
A．虚证转实B．实证转虚C．虚实夹杂D．表邪入里
