厂商通过卖出额外一单位产品所获得的收益叫做()。
A.净利润
B.分摊成本
C.边际收益
D.平均收益
参考答案:C
John agreed to the suggestion that his students ________ two weeks to prepare for the exam. [ ]
A. give
B. should give
C. be given
D. would be given
安全阀安全的位置是()
A.气控空间
B.液控空间
C.筒体底部