下列文献载体类型中,属于早期文献形态的是()
A.甲骨
B.缩微文献
C.声像文献
D.电子文献
参考答案:A
过点M(3,-2,1)且与直线平行的直线方程是()。
A.A
B.B
C.C
D.D
The MOST important feature of the material used for making the binnacle of a standard magnetic compass is that it is().
A.nonmagnetic
B.weatherproof
C.corrosion resistant
D.capable of being permanently affixed to the vessel