少量的金属钠长期放置在空气中,最终的产物是 ( )
A.Na2CO3
B.NaOH
C.Na2O
D.NaHCO3
答案:A
The Voice of China has set up a stage _______ some people can achieve their dreams.
A.which
B.when
C.that
D.where
非镀锌金属电缆桥架间连接板的两端应跨接铜芯接地线,接地线最小允许截面积小于()mm2。