铸造卡环一般安放在倒凹区的深度为
A.0.5~0.75mm B.0.25~0.5mm C.1~1.5mm D.2mm E.0.5mm
参考答案:B
He wants to buy a computer ______ his son.[ ]
A. to
B. for
C. on
中世纪大学的特征是()
A.自治性
B.国际性
C.民主性
D.职业性