—______?
—They are chairs. [ ]
A. Who are they
B. What are those
C. Where are these
答案:B
( )主要反映出主产品的层次结构、所有零部件的结构关系和数量组成。
A.BOM
B.MPS
C.MRP
D.库存文件
常见的有害杂质为()的化合物。