____________________ sell products to the public.____________________ often change each month.
________ is a money-making division within a company.________ is the revenue per product after variable expenses.
The total number of products sold is called_____________________________________________ .Revenue minus fixed and variable expeses is_____________________________________________ .
1949年长沙陈家大山楚墓出土的《人物龙凤帛画》和1973年长沙子弹库1号楚墓出土的《人物御龙帛画》是目前所知最重要的两幅什么时期绘画作品?