压缩机轴瓦材质为()
A.碳钢
B.硬质合金
C.塑料
D.搪瓷
参考答案:B
NetWare文件系统结构的基本构件块是________。
A.Volumes
B.Directories
C.Files
D.Databases
The package specification in the international trade is () than domestically.
A.lower
B.higher
C.smaller
D.bigger